Make DataType and Reference generic

src/etc/testcases/taskdefs/tar.xml

@@ -172,6 +172,12 @@
     <untar src="${output}/test11.tar.bz2" dest="${output}/untar" compression="bzip2"/>
   </target>
 
+  <target name="testTarFilesetWithReference">
+    <fileset id="xml.fileset" dir="." includes="*.xml"/>
+    <tar destfile="${output}/testtar.tar">
+      <tarfileset prefix="pre" refid="xml.fileset"/>
+    </tar>
+  </target>
 
   <target name="feather">
     <tar destfile="${output}/asf-logo.gif.tar"

src/main/org/apache/tools/ant/taskdefs/Classloader.java

@@ -124,7 +124,7 @@ public class Classloader extends Task {
      * @throws BuildException if there is a problem.
      */
     public void setClasspathRef(Reference pathRef) throws BuildException {
-        classpath = (Path) pathRef.getReferencedObject(getProject());
+        classpath = pathRef.getReferencedObject(getProject());
     }
 
     /**

src/main/org/apache/tools/ant/taskdefs/Input.java

@@ -105,7 +105,7 @@ public class Input extends Task {
             }
             if (refid != null) {
                try {
-                   return (InputHandler) (getProject().getReference(refid));
+                   return getProject().getReference(refid);
                } catch (final ClassCastException e) {
                    throw new BuildException(
                        refid + " does not denote an InputHandler", e);

src/main/org/apache/tools/ant/taskdefs/optional/extension/ExtensionAdapter.java

@@ -180,7 +180,7 @@ public class ExtensionAdapter extends DataType {
     Extension toExtension()
         throws BuildException {
         if (isReference()) {
-            return ((ExtensionAdapter) getCheckedRef()).toExtension();
+            return getRef().toExtension();
         }
         dieOnCircularReference();
         if (null == extensionName) {
@@ -213,4 +213,8 @@ public class ExtensionAdapter extends DataType {
     public String toString() {
         return "{" + toExtension() + "}";
     }
+
+    private ExtensionAdapter getRef() {
+        return getCheckedRef(ExtensionAdapter.class);
+    }
 }

src/main/org/apache/tools/ant/taskdefs/optional/extension/ExtensionSet.java

@@ -95,7 +95,7 @@ public class ExtensionSet
     public Extension[] toExtensions(final Project proj)
         throws BuildException {
         if (isReference()) {
-            return ((ExtensionSet) getCheckedRef()).toExtensions(proj);
+            return getRef().toExtensions(proj);
         }
         dieOnCircularReference();
         final List<Extension> extensionsList = ExtensionUtil.toExtensions(extensions);
@@ -141,6 +141,10 @@ public class ExtensionSet
         }
     }
 
+    private ExtensionSet getRef() {
+        return getCheckedRef(ExtensionSet.class);
+    }
+
     /**
      * @see java.lang.Object#toString()
      * @return the extensions in a string.

src/main/org/apache/tools/ant/types/AbstractFileSet.java

@@ -573,11 +573,17 @@ public abstract class AbstractFileSet extends DataType
     /**
      * Performs the check for circular references and returns the
      * referenced FileSet.
+     * This method can overridden together with {@link ArchiveFileSet#getRef() getRef()}
+     * providing implementations containing the special support
+     * for FileSet references, which can be handled by all ArchiveFileSets.
+     * NB! This method must be overridden in subclasses such as FileSet and DirSet
+     * to distinguish between the data types.
+     * @return the dereferenced object.
      * @param p the current project
      * @return the referenced FileSet
      */
     protected AbstractFileSet getRef(Project p) {
-        return (AbstractFileSet) getCheckedRef(p);
+        return getCheckedRef(AbstractFileSet.class, getDataTypeName(), p);
     }
 
     // SelectorContainer methods
@@ -901,8 +907,7 @@ public abstract class AbstractFileSet extends DataType
             return getRef(getProject()).toString();
         }
         dieOnCircularReference();
-        DirectoryScanner ds = getDirectoryScanner(getProject());
-        return String.join(";", ds.getIncludedFiles());
+        return String.join(";", getDirectoryScanner().getIncludedFiles());
     }
 
     /**

src/main/org/apache/tools/ant/types/AntFilterReader.java

@@ -55,7 +55,7 @@ public final class AntFilterReader extends DataType {
      */
     public String getClassName() {
         if (isReference()) {
-            return ((AntFilterReader) getCheckedRef()).getClassName();
+            return getRef().getClassName();
         }
         dieOnCircularReference();
         return className;
@@ -110,7 +110,7 @@ public final class AntFilterReader extends DataType {
      */
     public Path getClasspath() {
         if (isReference()) {
-            ((AntFilterReader) getCheckedRef()).getClasspath();
+            getRef().getClasspath();
         }
         dieOnCircularReference();
         return classpath;
@@ -135,7 +135,7 @@ public final class AntFilterReader extends DataType {
      */
     public Parameter[] getParams() {
         if (isReference()) {
-            ((AntFilterReader) getCheckedRef()).getParams();
+            getRef().getParams();
         }
         dieOnCircularReference();
         return parameters.toArray(new Parameter[parameters.size()]);
@@ -173,4 +173,8 @@ public final class AntFilterReader extends DataType {
             setChecked(true);
         }
     }
+
+    private AntFilterReader getRef() {
+        return getCheckedRef(AntFilterReader.class);
+    }
 }

src/main/org/apache/tools/ant/types/ArchiveFileSet.java

@@ -189,7 +189,7 @@ public abstract class ArchiveFileSet extends FileSet {
      */
     public File getSrc() {
         if (isReference()) {
-            return ((ArchiveFileSet) getCheckedRef()).getSrc();
+            return getCheckedRef(ArchiveFileSet.class).getSrc();
         }
         dieOnCircularReference();
         if (src == null) {
@@ -201,18 +201,17 @@ public abstract class ArchiveFileSet extends FileSet {
     /**
      * Performs the check for circular references and returns the
      * referenced object.
-     * This is an override which does not delegate to the superclass; instead it invokes
-     * {@link #getRef(Project)}, because that contains the special support for fileset
-     * references, which can be handled by all ArchiveFileSets.
-     * @param p the Ant Project instance against which to resolve references.
+     * This method must be overridden together with
+     * {@link AbstractFileSet#getRef(Project) getRef(Project)}
+     * providing implementations containing the special support
+     * for FileSet references, which can be handled by all ArchiveFileSets.
+     * NB! This method cannot be implemented in AbstractFileSet in order to allow
+     * FileSet and DirSet to implement it as a private method.
      * @return the dereferenced object.
      * @throws BuildException if the reference is invalid (circular ref, wrong class, etc).
-     * @since Ant 1.8
      */
-    // TODO is the above true? AFAICT the calls look circular :/
-    @Override
-    protected Object getCheckedRef(Project p) {
-        return getRef(p);
+    protected AbstractFileSet getRef() {
+        return getCheckedRef(AbstractFileSet.class);
     }
 
     /**
@@ -286,7 +285,7 @@ public abstract class ArchiveFileSet extends FileSet {
      */
     public String getEncoding() {
         if (isReference()) {
-            AbstractFileSet ref = getRef(getProject());
+            AbstractFileSet ref = getRef();
             return ref instanceof ArchiveFileSet ? ((ArchiveFileSet) ref).getEncoding() : null;
         }
         return encoding;
@@ -339,13 +338,12 @@ public abstract class ArchiveFileSet extends FileSet {
     @Override
     public Iterator<Resource> iterator() {
         if (isReference()) {
-            return ((ResourceCollection) (getRef(getProject()))).iterator();
+            return ((ResourceCollection) getRef()).iterator();
         }
         if (src == null) {
             return super.iterator();
         }
-        ArchiveScanner as = (ArchiveScanner) getDirectoryScanner(getProject());
-        return as.getResourceFiles(getProject());
+        return ((ArchiveScanner) getDirectoryScanner()).getResourceFiles(getProject());
     }
 
     /**
@@ -356,13 +354,12 @@ public abstract class ArchiveFileSet extends FileSet {
     @Override
     public int size() {
         if (isReference()) {
-            return ((ResourceCollection) (getRef(getProject()))).size();
+            return ((ResourceCollection) getRef()).size();
         }
         if (src == null) {
             return super.size();
         }
-        ArchiveScanner as = (ArchiveScanner) getDirectoryScanner(getProject());
-        return as.getIncludedFilesCount();
+        return getDirectoryScanner().getIncludedFilesCount();
     }
 
     /**
@@ -376,7 +373,7 @@ public abstract class ArchiveFileSet extends FileSet {
     @Override
     public boolean isFilesystemOnly() {
         if (isReference()) {
-            return ((ArchiveFileSet) getCheckedRef()).isFilesystemOnly();
+            return ((ArchiveFileSet) getRef()).isFilesystemOnly();
         }
         dieOnCircularReference();
         return src == null;
@@ -427,7 +424,7 @@ public abstract class ArchiveFileSet extends FileSet {
      */
     public boolean hasFileModeBeenSet() {
         if (isReference()) {
-            return ((ArchiveFileSet) getRef(getProject())).hasFileModeBeenSet();
+            return ((ArchiveFileSet) getRef()).hasFileModeBeenSet();
         }
         dieOnCircularReference();
         return fileModeHasBeenSet;
@@ -478,7 +475,7 @@ public abstract class ArchiveFileSet extends FileSet {
      */
     public boolean hasDirModeBeenSet() {
         if (isReference()) {
-            return ((ArchiveFileSet) getRef(getProject())).hasDirModeBeenSet();
+            return ((ArchiveFileSet) getRef()).hasDirModeBeenSet();
         }
         dieOnCircularReference();
         return dirModeHasBeenSet;
@@ -507,8 +504,7 @@ public abstract class ArchiveFileSet extends FileSet {
     @Override
     public Object clone() {
         if (isReference()) {
-            return getCheckedRef(ArchiveFileSet.class, getDataTypeName(),
-                getProject()).clone();
+            return getCheckedRef(ArchiveFileSet.class).clone();
         }
         return super.clone();
     }

src/main/org/apache/tools/ant/types/DataType.java

@@ -196,24 +196,44 @@ public abstract class DataType extends ProjectComponent implements Cloneable {
     /**
      * Performs the check for circular references and returns the
      * referenced object.
+     * @param <T> required reference type
      * @return the dereferenced object.
      * @throws BuildException if the reference is invalid (circular ref, wrong class, etc).
      * @since Ant 1.7
+     * @deprecated use getCheckedRef(Class)
      */
-    protected Object getCheckedRef() {
+    @Deprecated
+    protected <T> T getCheckedRef() {
         return getCheckedRef(getProject());
     }
 
     /**
      * Performs the check for circular references and returns the
      * referenced object.
+     * @param <T> required reference type
+     * @param requiredClass the class that this reference should be a subclass of.
+     * @return the dereferenced object.
+     * @throws BuildException if the reference is invalid (circular ref, wrong class, etc).
+     * @since Ant 1.10.6
+     */
+    protected <T> T getCheckedRef(final Class<T> requiredClass) {
+        return getCheckedRef(requiredClass, getDataTypeName(), getProject());
+    }
+
+    /**
+     * Performs the check for circular references and returns the
+     * referenced object.
+     * @param <T> required reference type
      * @param p the Ant Project instance against which to resolve references.
      * @return the dereferenced object.
      * @throws BuildException if the reference is invalid (circular ref, wrong class, etc).
      * @since Ant 1.7
+     * @deprecated use getCheckedRef(Class)
      */
-    protected Object getCheckedRef(Project p) {
-        return getCheckedRef(getClass(), getDataTypeName(), p);
+    @Deprecated
+    @SuppressWarnings("unchecked")
+    protected <T> T getCheckedRef(Project p) {
+        return getCheckedRef((Class<T>) getClass(), getDataTypeName(), p);
     }
 
     /**
@@ -244,16 +264,15 @@ public abstract class DataType extends ProjectComponent implements Cloneable {
      *                        or if <code>project</code> is <code>null</code>.
      * @since Ant 1.7
      */
-    @SuppressWarnings("unchecked")
     protected <T> T getCheckedRef(final Class<T> requiredClass,
                                   final String dataTypeName, final Project project) {
         if (project == null) {
             throw new BuildException("No Project specified");
         }
         dieOnCircularReference(project);
-        Object o = ref.getReferencedObject(project);
+        T o = ref.getReferencedObject(project);
         if (requiredClass.isAssignableFrom(o.getClass())) {
-            return (T) o;
+            return o;
         }
         log("Class " + displayName(o.getClass())
                         + " is not a subclass of "

src/main/org/apache/tools/ant/types/DirSet.java

@@ -20,6 +20,7 @@ package org.apache.tools.ant.types;
 
 import java.util.Iterator;
 
+import org.apache.tools.ant.Project;
 import org.apache.tools.ant.types.resources.FileResourceIterator;
 
 /**
@@ -53,7 +54,7 @@ public class DirSet extends AbstractFileSet implements ResourceCollection {
     @Override
     public Object clone() {
         if (isReference()) {
-            return getRef(getProject()).clone();
+            return getRef().clone();
         }
         return super.clone();
     }
@@ -66,10 +67,10 @@ public class DirSet extends AbstractFileSet implements ResourceCollection {
     @Override
     public Iterator<Resource> iterator() {
         if (isReference()) {
-            return ((DirSet) getRef(getProject())).iterator();
+            return getRef().iterator();
         }
         return new FileResourceIterator(getProject(), getDir(getProject()),
-            getDirectoryScanner(getProject()).getIncludedDirectories());
+            getDirectoryScanner().getIncludedDirectories());
     }
 
     /**
@@ -80,9 +81,9 @@ public class DirSet extends AbstractFileSet implements ResourceCollection {
     @Override
     public int size() {
         if (isReference()) {
-            return ((DirSet) getRef(getProject())).size();
+            return getRef().size();
         }
-        return getDirectoryScanner(getProject()).getIncludedDirsCount();
+        return getDirectoryScanner().getIncludedDirsCount();
     }
 
     /**
@@ -102,7 +103,16 @@ public class DirSet extends AbstractFileSet implements ResourceCollection {
      */
     @Override
     public String toString() {
-        return String.join(";", getDirectoryScanner(getProject()).getIncludedDirectories());
+        return String.join(";", getDirectoryScanner().getIncludedDirectories());
+    }
+
+    @Override
+    protected AbstractFileSet getRef(Project p) {
+        return getCheckedRef(DirSet.class, getDataTypeName(), p);
+    }
+
+    private DirSet getRef() {
+        return getCheckedRef(DirSet.class);
     }
 
 }

src/main/org/apache/tools/ant/types/FileList.java

@@ -136,16 +136,6 @@ public class FileList extends DataType implements ResourceCollection {
         return filenames.toArray(new String[filenames.size()]);
     }
 
-    /**
-     * Performs the check for circular references and returns the
-     * referenced FileList.
-     * @param p the current project
-     * @return the FileList represented by a referenced filelist.
-     */
-    protected FileList getRef(Project p) {
-        return (FileList) getCheckedRef(p);
-    }
-
     /**
      * Inner class corresponding to the <file> nested element.
      */
@@ -191,7 +181,7 @@ public class FileList extends DataType implements ResourceCollection {
     @Override
     public Iterator<Resource> iterator() {
         if (isReference()) {
-            return getRef(getProject()).iterator();
+            return getRef().iterator();
         }
         return new FileResourceIterator(getProject(), dir,
             filenames.toArray(new String[filenames.size()]));
@@ -205,7 +195,7 @@ public class FileList extends DataType implements ResourceCollection {
     @Override
     public int size() {
         if (isReference()) {
-            return getRef(getProject()).size();
+            return getRef().size();
         }
         return filenames.size();
     }
@@ -220,4 +210,12 @@ public class FileList extends DataType implements ResourceCollection {
         return true;
     }
 
+    private FileList getRef() {
+        return getCheckedRef(FileList.class);
+    }
+
+    private FileList getRef(Project p) {
+        return getCheckedRef(FileList.class, getDataTypeName(), p);
+    }
+
 }

src/main/org/apache/tools/ant/types/FileSet.java

@@ -20,6 +20,7 @@ package org.apache.tools.ant.types;
 
 import java.util.Iterator;
 
+import org.apache.tools.ant.Project;
 import org.apache.tools.ant.types.resources.FileResourceIterator;
 
 /**
@@ -52,7 +53,7 @@ public class FileSet extends AbstractFileSet implements ResourceCollection {
     @Override
     public Object clone() {
         if (isReference()) {
-            return getRef(getProject()).clone();
+            return getRef().clone();
         }
         return super.clone();
     }
@@ -65,10 +66,10 @@ public class FileSet extends AbstractFileSet implements ResourceCollection {
     @Override
     public Iterator<Resource> iterator() {
         if (isReference()) {
-            return ((FileSet) getRef(getProject())).iterator();
+            return getRef().iterator();
         }
         return new FileResourceIterator(getProject(), getDir(getProject()),
-            getDirectoryScanner(getProject()).getIncludedFiles());
+            getDirectoryScanner().getIncludedFiles());
     }
 
     /**
@@ -79,9 +80,9 @@ public class FileSet extends AbstractFileSet implements ResourceCollection {
     @Override
     public int size() {
         if (isReference()) {
-            return ((FileSet) getRef(getProject())).size();
+            return getRef().size();
         }
-        return getDirectoryScanner(getProject()).getIncludedFilesCount();
+        return getDirectoryScanner().getIncludedFilesCount();
     }
 
     /**
@@ -94,4 +95,13 @@ public class FileSet extends AbstractFileSet implements ResourceCollection {
         return true;
     }
 
+    @Override
+    protected AbstractFileSet getRef(Project p) {
+        return getCheckedRef(FileSet.class, getDataTypeName(), p);
+    }
+
+    private FileSet getRef() {
+        return getCheckedRef(FileSet.class);
+    }
+
 }

src/main/org/apache/tools/ant/types/FilterChain.java

@@ -68,7 +68,7 @@ public class FilterChain extends DataType {
      */
     public Vector<Object> getFilterReaders() {
         if (isReference()) {
-            return ((FilterChain) getCheckedRef()).getFilterReaders();
+            return getRef().getFilterReaders();
         }
         dieOnCircularReference();
         return filterReaders;
@@ -412,4 +412,8 @@ public class FilterChain extends DataType {
             setChecked(true);
         }
     }
+
+    private FilterChain getRef() {
+        return getCheckedRef(FilterChain.class);
+    }
 }

src/main/org/apache/tools/ant/types/FilterSet.java

@@ -236,7 +236,7 @@ public class FilterSet extends DataType implements Cloneable {
      * @return the filterset from the reference.
      */
     protected FilterSet getRef() {
-        return getCheckedRef(FilterSet.class, "filterset");
+        return getCheckedRef(FilterSet.class);
     }
 
     /**

src/main/org/apache/tools/ant/types/Mapper.java

@@ -276,7 +276,7 @@ public class Mapper extends DataType {
      */
     @Deprecated
     protected Mapper getRef() {
-        return getCheckedRef(Mapper.class, getDataTypeName());
+        return getCheckedRef(Mapper.class);
     }
 
     /**

src/main/org/apache/tools/ant/types/Path.java

@@ -376,7 +376,7 @@ public class Path extends DataType implements Cloneable, ResourceCollection {
      */
     public String[] list() {
         if (isReference()) {
-            return ((Path) getCheckedRef()).list();
+            return getRef().list();
         }
         return assertFilesystemOnly(union) == null
             ? new String[0] : union.list();
@@ -389,7 +389,7 @@ public class Path extends DataType implements Cloneable, ResourceCollection {
      */
     @Override
     public String toString() {
-        return isReference() ? getCheckedRef().toString()
+        return isReference() ? getRef().toString()
             : union == null ? "" : union.toString();
     }
 
@@ -463,7 +463,7 @@ public class Path extends DataType implements Cloneable, ResourceCollection {
     @Override
     public synchronized int size() {
         if (isReference()) {
-            return ((Path) getCheckedRef()).size();
+            return getRef().size();
         }
         dieOnCircularReference();
         return union == null ? 0 : assertFilesystemOnly(union).size();
@@ -690,7 +690,7 @@ public class Path extends DataType implements Cloneable, ResourceCollection {
     @Override
     public final synchronized Iterator<Resource> iterator() {
         if (isReference()) {
-            return ((Path) getCheckedRef()).iterator();
+            return getRef().iterator();
         }
         dieOnCircularReference();
         if (getPreserveBC()) {
@@ -707,7 +707,7 @@ public class Path extends DataType implements Cloneable, ResourceCollection {
     @Override
     public synchronized boolean isFilesystemOnly() {
         if (isReference()) {
-            return ((Path) getCheckedRef()).isFilesystemOnly();
+            return getRef().isFilesystemOnly();
         }
         dieOnCircularReference();
         assertFilesystemOnly(union);
@@ -764,4 +764,8 @@ public class Path extends DataType implements Cloneable, ResourceCollection {
         return path != null && (path.contains("*") || path.contains("?"));
     }
 
+    private Path getRef() {
+        return getCheckedRef(Path.class);
+    }
+
 }

src/main/org/apache/tools/ant/types/PatternSet.java

@@ -505,7 +505,7 @@ public class PatternSet extends DataType implements Cloneable {
      * referenced PatternSet.
      */
     private PatternSet getRef(Project p) {
-        return (PatternSet) getCheckedRef(p);
+        return getCheckedRef(PatternSet.class, getDataTypeName(), p);
     }
 
     /**

src/main/org/apache/tools/ant/types/PropertySet.java

@@ -425,7 +425,7 @@ public class PropertySet extends DataType implements ResourceCollection {
      * @return the referenced PropertySet.
      */
     protected PropertySet getRef() {
-        return getCheckedRef(PropertySet.class, "propertyset");
+        return getCheckedRef(PropertySet.class);
     }
 
     /**

src/main/org/apache/tools/ant/types/RedirectorElement.java

@@ -624,7 +624,7 @@ public class RedirectorElement extends DataType {
      * @return the referenced RedirectorElement.
      */
     private RedirectorElement getRef() {
-        return (RedirectorElement) getCheckedRef();
+        return getCheckedRef(RedirectorElement.class);
     }
 
 }

src/main/org/apache/tools/ant/types/Reference.java

@@ -107,12 +107,12 @@ public class Reference {
      * @return the dereferenced object.
      * @throws BuildException if the reference cannot be dereferenced.
      */
-    public Object getReferencedObject(Project fallback) throws BuildException {
+    public <T> T getReferencedObject(Project fallback) throws BuildException {
         if (refid == null) {
             throw new BuildException("No reference specified");
         }
 
-        Object o = project == null ? fallback.getReference(refid) : project.getReference(refid);
+        T o = project == null ? fallback.getReference(refid) : project.getReference(refid);
         if (o == null) {
             throw new BuildException("Reference " + refid + " not found.");
         }
@@ -126,7 +126,7 @@ public class Reference {
      * @throws BuildException if the project is null or the reference cannot be dereferenced
      * @since Ant 1.6.3
      */
-    public Object getReferencedObject() throws BuildException {
+    public <T> T getReferencedObject() throws BuildException {
         if (project == null) {
             throw new BuildException("No project set on reference to " + refid);
         }

src/main/org/apache/tools/ant/types/RegularExpression.java

@@ -130,6 +130,6 @@ public class RegularExpression extends DataType {
      * @return resolved RegularExpression instance
      */
     public RegularExpression getRef(Project p) {
-        return (RegularExpression) getCheckedRef(p);
+        return getCheckedRef(RegularExpression.class, getDataTypeName(), p);
     }
 }

src/main/org/apache/tools/ant/types/Resource.java

@@ -141,7 +141,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      * @return the name of this resource.
      */
     public String getName() {
-        return isReference() ? getCheckedRef().getName() : name;
+        return isReference() ? getRef().getName() : name;
     }
 
     /**
@@ -160,7 +160,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     public boolean isExists() {
         if (isReference()) {
-            return getCheckedRef().isExists();
+            return getRef().isExists();
         }
         //default true:
         return exists == null || exists;
@@ -187,7 +187,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     public long getLastModified() {
         if (isReference()) {
-            return getCheckedRef().getLastModified();
+            return getRef().getLastModified();
         }
         if (!isExists() || lastmodified == null) {
             return UNKNOWN_DATETIME;
@@ -211,7 +211,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     public boolean isDirectory() {
         if (isReference()) {
-            return getCheckedRef().isDirectory();
+            return getRef().isDirectory();
         }
         //default false:
         return directory != null && directory;
@@ -244,7 +244,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     public long getSize() {
         if (isReference()) {
-            return getCheckedRef().getSize();
+            return getRef().getSize();
         }
         return isExists()
             ? (size != null ? size : UNKNOWN_SIZE)
@@ -275,7 +275,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
     @Override
     public int compareTo(Resource other) {
         if (isReference()) {
-            return getCheckedRef().compareTo(other);
+            return getRef().compareTo(other);
         }
         return toString().compareTo(other.toString());
     }
@@ -292,7 +292,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
             return true;
         }
         if (isReference()) {
-            return getCheckedRef().equals(other);
+            return getRef().equals(other);
         }
         return other != null && other.getClass().equals(getClass())
             && compareTo((Resource) other) == 0;
@@ -306,7 +306,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
     @Override
     public int hashCode() {
         if (isReference()) {
-            return getCheckedRef().hashCode();
+            return getRef().hashCode();
         }
         String name = getName();
         return MAGIC * (name == null ? NULL_NAME : name.hashCode());
@@ -323,7 +323,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     public InputStream getInputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getInputStream();
+            return getRef().getInputStream();
         }
         throw new UnsupportedOperationException();
     }
@@ -339,7 +339,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     public OutputStream getOutputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getOutputStream();
+            return getRef().getOutputStream();
         }
         throw new UnsupportedOperationException();
     }
@@ -351,7 +351,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     @Override
     public Iterator<Resource> iterator() {
-        return isReference() ? getCheckedRef().iterator()
+        return isReference() ? getRef().iterator()
             : Collections.singleton(this).iterator();
     }
 
@@ -362,7 +362,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     @Override
     public int size() {
-        return isReference() ? getCheckedRef().size() : 1;
+        return isReference() ? getRef().size() : 1;
     }
 
     /**
@@ -372,7 +372,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      */
     @Override
     public boolean isFilesystemOnly() {
-        return (isReference() && getCheckedRef().isFilesystemOnly())
+        return (isReference() && getRef().isFilesystemOnly())
             || this.as(FileProvider.class) != null;
     }
 
@@ -384,7 +384,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
     @Override
     public String toString() {
         if (isReference()) {
-            return getCheckedRef().toString();
+            return getRef().toString();
         }
         String n = getName();
         return n == null ? "(anonymous)" : n;
@@ -398,7 +398,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
      * @since Ant 1.7
      */
     public final String toLongString() {
-        return isReference() ? getCheckedRef().toLongString()
+        return isReference() ? getRef().toLongString()
             : getDataTypeName() + " \"" + toString() + '"';
     }
 
@@ -449,8 +449,7 @@ public class Resource extends DataType implements Comparable<Resource>, Resource
         return Optional.ofNullable(as(clazz));
     }
 
-    @Override
-    protected Resource getCheckedRef() {
-        return (Resource) super.getCheckedRef();
+    protected Resource getRef() {
+        return getCheckedRef(Resource.class);
     }
 }

src/main/org/apache/tools/ant/types/Substitution.java

@@ -71,6 +71,6 @@ public class Substitution extends DataType {
      * @return the resolved reference
      */
     public Substitution getRef(Project p) {
-        return (Substitution) getCheckedRef(p);
+        return getCheckedRef(Substitution.class, getDataTypeName(), p);
     }
 }

src/main/org/apache/tools/ant/types/TarFileSet.java

@@ -78,7 +78,7 @@ public class TarFileSet extends ArchiveFileSet {
      */
     public String getUserName() {
         if (isReference()) {
-            return ((TarFileSet) getCheckedRef()).getUserName();
+            return ((TarFileSet) getRef()).getUserName();
         }
         return userName;
     }
@@ -106,7 +106,7 @@ public class TarFileSet extends ArchiveFileSet {
      */
     public int getUid() {
         if (isReference()) {
-            return ((TarFileSet) getCheckedRef()).getUid();
+            return ((TarFileSet) getRef()).getUid();
         }
         return uid;
     }
@@ -134,7 +134,7 @@ public class TarFileSet extends ArchiveFileSet {
      */
     public String getGroup() {
         if (isReference()) {
-            return ((TarFileSet) getCheckedRef()).getGroup();
+            return ((TarFileSet) getRef()).getGroup();
         }
         return groupName;
     }
@@ -162,7 +162,7 @@ public class TarFileSet extends ArchiveFileSet {
      */
     public int getGid() {
         if (isReference()) {
-            return ((TarFileSet) getCheckedRef()).getGid();
+            return ((TarFileSet) getRef()).getGid();
         }
         return gid;
     }
@@ -223,6 +223,16 @@ public class TarFileSet extends ArchiveFileSet {
         throw new BuildException(msg);
     }
 
+    /**
+     * A TarFileset accepts another TarFileSet or a FileSet as reference
+     * FileSets are often used by the war task for the lib attribute
+     * @return the abstract fileset instance
+     */
+    @Override
+    protected AbstractFileSet getRef() {
+        return getRef(getProject());
+    }
+
     /**
      * Configure a fileset based on this fileset.
      * If the fileset is a TarFileSet copy in the tarfileset
@@ -249,7 +259,7 @@ public class TarFileSet extends ArchiveFileSet {
     @Override
     public Object clone() {
         if (isReference()) {
-            return getRef(getProject()).clone();
+            return getRef().clone();
         }
         return super.clone();
     }

src/main/org/apache/tools/ant/types/XMLCatalog.java

@@ -474,7 +474,7 @@ public class XMLCatalog extends DataType
         if (!isReference()) {
             return this;
         }
-        return getCheckedRef(XMLCatalog.class, "xmlcatalog");
+        return getCheckedRef(XMLCatalog.class);
     }
 
     /**

src/main/org/apache/tools/ant/types/ZipFileSet.java

@@ -87,6 +87,16 @@ public class ZipFileSet extends ArchiveFileSet {
         throw new BuildException(msg);
     }
 
+    /**
+     * A ZipFileset accepts another ZipFileSet or a FileSet as reference
+     * FileSets are often used by the war task for the lib attribute
+     * @return the abstract fileset instance
+     */
+    @Override
+    protected AbstractFileSet getRef() {
+        return getRef(getProject());
+    }
+
     /**
      * Return a ZipFileSet that has the same properties
      * as this one.
@@ -95,7 +105,7 @@ public class ZipFileSet extends ArchiveFileSet {
     @Override
     public Object clone() {
         if (isReference()) {
-            return getRef(getProject()).clone();
+            return getRef().clone();
         }
         return super.clone();
     }

src/main/org/apache/tools/ant/types/optional/depend/ClassfileSet.java

@@ -162,8 +162,7 @@ public class ClassfileSet extends FileSet {
      */
     @Override
     public Object clone() {
-        return new ClassfileSet(isReference()
-            ? (ClassfileSet) (getRef(getProject())) : this);
+        return new ClassfileSet(isReference() ? getRef() : this);
     }
 
     @Override
@@ -182,4 +181,8 @@ public class ClassfileSet extends FileSet {
             setChecked(true);
         }
     }
+
+    private ClassfileSet getRef() {
+        return getCheckedRef(ClassfileSet.class);
+    }
 }

src/main/org/apache/tools/ant/types/resources/AbstractClasspathResource.java

@@ -84,7 +84,7 @@ public abstract class AbstractClasspathResource extends Resource {
      */
     public Path getClasspath() {
         if (isReference()) {
-            return ((AbstractClasspathResource) getCheckedRef()).getClasspath();
+            return getRef().getClasspath();
         }
         dieOnCircularReference();
         return classpath;
@@ -96,7 +96,7 @@ public abstract class AbstractClasspathResource extends Resource {
      */
     public Reference getLoader() {
         if (isReference()) {
-            return ((AbstractClasspathResource) getCheckedRef()).getLoader();
+            return getRef().getLoader();
         }
         dieOnCircularReference();
         return loader;
@@ -151,7 +151,7 @@ public abstract class AbstractClasspathResource extends Resource {
      */
     public boolean isExists() {
         if (isReference()) {
-            return  getCheckedRef().isExists();
+            return getRef().isExists();
         }
         dieOnCircularReference();
         try (InputStream is = getInputStream()) {
@@ -169,7 +169,7 @@ public abstract class AbstractClasspathResource extends Resource {
      */
     public InputStream getInputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getInputStream();
+            return getRef().getInputStream();
         }
         dieOnCircularReference();
 
@@ -204,7 +204,7 @@ public abstract class AbstractClasspathResource extends Resource {
     protected ClassLoaderWithFlag getClassLoader() {
         ClassLoader cl = null;
         if (loader != null) {
-            cl = (ClassLoader) loader.getReferencedObject();
+            cl = loader.getReferencedObject();
         }
         boolean clNeedsCleanup = false;
         if (cl == null) {
@@ -252,6 +252,11 @@ public abstract class AbstractClasspathResource extends Resource {
         }
     }
 
+    @Override
+    protected AbstractClasspathResource getRef() {
+        return getCheckedRef(AbstractClasspathResource.class);
+    }
+
     public static class ClassLoaderWithFlag {
         private final ClassLoader loader;
         private final boolean cleanup;

src/main/org/apache/tools/ant/types/resources/AbstractResourceCollectionWrapper.java

@@ -89,7 +89,7 @@ public abstract class AbstractResourceCollectionWrapper
     @Override
     public final synchronized Iterator<Resource> iterator() {
         if (isReference()) {
-            return ((AbstractResourceCollectionWrapper) getCheckedRef()).iterator();
+            return getRef().iterator();
         }
         dieOnCircularReference();
         return new FailFast(this, createIterator());
@@ -112,7 +112,7 @@ public abstract class AbstractResourceCollectionWrapper
     @Override
     public synchronized int size() {
         if (isReference()) {
-            return ((AbstractResourceCollectionWrapper) getCheckedRef()).size();
+            return getRef().size();
         }
         dieOnCircularReference();
         return getSize();
@@ -132,7 +132,7 @@ public abstract class AbstractResourceCollectionWrapper
      */
     public synchronized boolean isFilesystemOnly() {
         if (isReference()) {
-            return ((BaseResourceCollectionContainer) getCheckedRef()).isFilesystemOnly();
+            return getRef().isFilesystemOnly();
         }
         dieOnCircularReference();
 
@@ -191,7 +191,7 @@ public abstract class AbstractResourceCollectionWrapper
     @Override
     public synchronized String toString() {
         if (isReference()) {
-            return getCheckedRef().toString();
+            return getRef().toString();
         }
         if (isEmpty()) {
             return "";
@@ -200,6 +200,10 @@ public abstract class AbstractResourceCollectionWrapper
             .collect(Collectors.joining(File.pathSeparator));
     }
 
+    private AbstractResourceCollectionWrapper getRef() {
+        return getCheckedRef(AbstractResourceCollectionWrapper.class);
+    }
+
     private BuildException oneNested() {
         return new BuildException(super.toString() + ONE_NESTED_MESSAGE);
     }

src/main/org/apache/tools/ant/types/resources/ArchiveResource.java

@@ -118,7 +118,7 @@ public abstract class ArchiveResource extends Resource {
      * @return the archive as a Resource.
      */
     public Resource getArchive() {
-        return isReference() ? getCheckedRef().getArchive() : archive;
+        return isReference() ? getRef().getArchive() : archive;
     }
 
     /**
@@ -128,7 +128,7 @@ public abstract class ArchiveResource extends Resource {
     @Override
     public long getLastModified() {
         if (isReference()) {
-            return getCheckedRef().getLastModified();
+            return getRef().getLastModified();
         }
         checkEntry();
         return super.getLastModified();
@@ -141,7 +141,7 @@ public abstract class ArchiveResource extends Resource {
     @Override
     public long getSize() {
         if (isReference()) {
-            return getCheckedRef().getSize();
+            return getRef().getSize();
         }
         checkEntry();
         return super.getSize();
@@ -154,7 +154,7 @@ public abstract class ArchiveResource extends Resource {
     @Override
     public boolean isDirectory() {
         if (isReference()) {
-            return getCheckedRef().isDirectory();
+            return getRef().isDirectory();
         }
         checkEntry();
         return super.isDirectory();
@@ -167,7 +167,7 @@ public abstract class ArchiveResource extends Resource {
     @Override
     public boolean isExists() {
         if (isReference()) {
-            return getCheckedRef().isExists();
+            return getRef().isExists();
         }
         checkEntry();
         return super.isExists();
@@ -179,7 +179,7 @@ public abstract class ArchiveResource extends Resource {
      */
     public int getMode() {
         if (isReference()) {
-            return getCheckedRef().getMode();
+            return getRef().getMode();
         }
         checkEntry();
         return mode;
@@ -220,7 +220,7 @@ public abstract class ArchiveResource extends Resource {
             return true;
         }
         if (isReference()) {
-            return getCheckedRef().equals(another);
+            return getRef().equals(another);
         }
         if (another == null || !another.getClass().equals(getClass())) {
             return false;
@@ -246,7 +246,7 @@ public abstract class ArchiveResource extends Resource {
      */
     @Override
     public String toString() {
-        return isReference() ? getCheckedRef().toString()
+        return isReference() ? getRef().toString()
             : getArchive().toString() + ':' + getName();
     }
 
@@ -301,7 +301,7 @@ public abstract class ArchiveResource extends Resource {
     }
 
     @Override
-    protected ArchiveResource getCheckedRef() {
-        return (ArchiveResource) super.getCheckedRef();
+    protected ArchiveResource getRef() {
+        return getCheckedRef(ArchiveResource.class);
     }
 }

src/main/org/apache/tools/ant/types/resources/Archives.java

@@ -81,7 +81,7 @@ public class Archives extends DataType
     @Override
     public int size() {
         if (isReference()) {
-            return getCheckedRef().size();
+            return getRef().size();
         }
         dieOnCircularReference();
         return streamArchives().mapToInt(ArchiveFileSet::size).sum();
@@ -94,7 +94,7 @@ public class Archives extends DataType
      */
     public Iterator<Resource> iterator() {
         if (isReference()) {
-            return getCheckedRef().iterator();
+            return getRef().iterator();
         }
         dieOnCircularReference();
         return streamArchives().flatMap(ResourceCollection::stream)
@@ -106,7 +106,7 @@ public class Archives extends DataType
      */
     public boolean isFilesystemOnly() {
         if (isReference()) {
-            return getCheckedRef().isFilesystemOnly();
+            return getRef().isFilesystemOnly();
         }
         dieOnCircularReference();
         // TODO check each archive in turn?
@@ -207,9 +207,8 @@ public class Archives extends DataType
         }
     }
 
-    @Override
-    protected Archives getCheckedRef() {
-        return (Archives) super.getCheckedRef();
+    private Archives getRef() {
+        return getCheckedRef(Archives.class);
     }
 
 }

src/main/org/apache/tools/ant/types/resources/BCFileSet.java

@@ -50,7 +50,7 @@ public class BCFileSet extends FileSet {
     @Override
     public Iterator<Resource> iterator() {
         if (isReference()) {
-            return ((FileSet) getRef(getProject())).iterator();
+            return getRef().iterator();
         }
         FileResourceIterator result = new FileResourceIterator(getProject(), getDir());
         result.addFiles(getDirectoryScanner().getIncludedFiles());
@@ -66,10 +66,14 @@ public class BCFileSet extends FileSet {
     @Override
     public int size() {
         if (isReference()) {
-            return ((FileSet) getRef(getProject())).size();
+            return getRef().size();
         }
         return getDirectoryScanner().getIncludedFilesCount()
             + getDirectoryScanner().getIncludedDirsCount();
     }
 
+    private FileSet getRef() {
+        return getCheckedRef(FileSet.class);
+    }
+
 }

src/main/org/apache/tools/ant/types/resources/BaseResourceCollectionContainer.java

@@ -136,7 +136,7 @@ public abstract class BaseResourceCollectionContainer
     @Override
     public final synchronized Iterator<Resource> iterator() {
         if (isReference()) {
-            return getCheckedRef().iterator();
+            return getRef().iterator();
         }
         dieOnCircularReference();
         return new FailFast(this, cacheCollection().iterator());
@@ -149,8 +149,7 @@ public abstract class BaseResourceCollectionContainer
     @Override
     public synchronized int size() {
         if (isReference()) {
-            return getCheckedRef(BaseResourceCollectionContainer.class,
-                getDataTypeName()).size();
+            return getRef().size();
         }
         dieOnCircularReference();
         return cacheCollection().size();
@@ -163,7 +162,7 @@ public abstract class BaseResourceCollectionContainer
     @Override
     public synchronized boolean isFilesystemOnly() {
         if (isReference()) {
-            return getCheckedRef().isFilesystemOnly();
+            return getRef().isFilesystemOnly();
         }
         dieOnCircularReference();
         //first the easy way, if all children are filesystem-only, return true:
@@ -240,7 +239,7 @@ public abstract class BaseResourceCollectionContainer
     @Override
     public synchronized String toString() {
         if (isReference()) {
-            return getCheckedRef().toString();
+            return getRef().toString();
         }
         if (cacheCollection().isEmpty()) {
             return "";
@@ -249,9 +248,8 @@ public abstract class BaseResourceCollectionContainer
             .collect(Collectors.joining(File.pathSeparator));
     }
 
-    @Override
-    protected BaseResourceCollectionContainer getCheckedRef() {
-        return (BaseResourceCollectionContainer) super.getCheckedRef();
+     private BaseResourceCollectionContainer getRef() {
+        return getCheckedRef(BaseResourceCollectionContainer.class);
     }
 
     private synchronized Collection<Resource> cacheCollection() {

src/main/org/apache/tools/ant/types/resources/FileResource.java

@@ -108,7 +108,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public File getFile() {
         if (isReference()) {
-            return getCheckedRef().getFile();
+            return getRef().getFile();
         }
         dieOnCircularReference();
         synchronized (this) {
@@ -139,7 +139,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
      */
     public File getBaseDir() {
         if (isReference()) {
-            return getCheckedRef().getBaseDir();
+            return getRef().getBaseDir();
         }
         dieOnCircularReference();
         return baseDir;
@@ -166,7 +166,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public String getName() {
         if (isReference()) {
-            return getCheckedRef().getName();
+            return getRef().getName();
         }
         File b = getBaseDir();
         return b == null ? getNotNullFile().getName()
@@ -179,7 +179,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
      */
     @Override
     public boolean isExists() {
-        return isReference() ? getCheckedRef().isExists()
+        return isReference() ? getRef().isExists()
             : getNotNullFile().exists();
     }
 
@@ -190,7 +190,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public long getLastModified() {
         return isReference()
-            ? getCheckedRef().getLastModified()
+            ? getRef().getLastModified()
             : getNotNullFile().lastModified();
     }
 
@@ -200,7 +200,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
      */
     @Override
     public boolean isDirectory() {
-        return isReference() ? getCheckedRef().isDirectory()
+        return isReference() ? getRef().isDirectory()
             : getNotNullFile().isDirectory();
     }
 
@@ -210,7 +210,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
      */
     @Override
     public long getSize() {
-        return isReference() ? getCheckedRef().getSize()
+        return isReference() ? getRef().getSize()
             : getNotNullFile().length();
     }
 
@@ -221,7 +221,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
      */
     @Override
     public InputStream getInputStream() throws IOException {
-        return isReference() ? getCheckedRef().getInputStream()
+        return isReference() ? getRef().getInputStream()
             : Files.newInputStream(getNotNullFile().toPath());
     }
 
@@ -236,7 +236,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public OutputStream getOutputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getOutputStream();
+            return getRef().getOutputStream();
         }
         return getOutputStream(false);
     }
@@ -247,7 +247,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public OutputStream getAppendOutputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getAppendOutputStream();
+            return getRef().getAppendOutputStream();
         }
         return getOutputStream(true);
     }
@@ -276,7 +276,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public int compareTo(Resource another) {
         if (isReference()) {
-            return getCheckedRef().compareTo(another);
+            return getRef().compareTo(another);
         }
         if (this.equals(another)) {
             return 0;
@@ -309,7 +309,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
             return true;
         }
         if (isReference()) {
-            return getCheckedRef().equals(another);
+            return getRef().equals(another);
         }
         if (another == null || !(another.getClass().equals(getClass()))) {
             return false;
@@ -327,7 +327,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public int hashCode() {
         if (isReference()) {
-            return getCheckedRef().hashCode();
+            return getRef().hashCode();
         }
         return MAGIC * (getFile() == null ? NULL_FILE : getFile().hashCode());
     }
@@ -339,7 +339,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public String toString() {
         if (isReference()) {
-            return getCheckedRef().toString();
+            return getRef().toString();
         }
         if (file == null) {
             return "(unbound file resource)";
@@ -355,7 +355,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public boolean isFilesystemOnly() {
         if (isReference()) {
-            return getCheckedRef().isFilesystemOnly();
+            return getRef().isFilesystemOnly();
         }
         dieOnCircularReference();
         return true;
@@ -368,7 +368,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     @Override
     public void touch(long modTime) {
         if (isReference()) {
-            getCheckedRef().touch(modTime);
+            getRef().touch(modTime);
             return;
         }
         if (!getNotNullFile().setLastModified(modTime)) {
@@ -408,7 +408,7 @@ public class FileResource extends Resource implements Touchable, FileProvider,
     }
 
     @Override
-    protected FileResource getCheckedRef() {
-        return (FileResource) super.getCheckedRef();
+    protected FileResource getRef() {
+        return getCheckedRef(FileResource.class);
     }
 }

src/main/org/apache/tools/ant/types/resources/Files.java

@@ -458,7 +458,7 @@ public class Files extends AbstractSelectorContainer
      * @return <code>FileCollection</code>.
      */
     protected Files getRef() {
-        return (Files) getCheckedRef();
+        return getCheckedRef(Files.class);
     }
 
     private synchronized void ensureDirectoryScannerSetup() {

src/main/org/apache/tools/ant/types/resources/JavaResource.java

@@ -82,7 +82,7 @@ public class JavaResource extends AbstractClasspathResource
     @Override
     public URL getURL() {
         if (isReference()) {
-            return getCheckedRef().getURL();
+            return getRef().getURL();
         }
         AbstractClasspathResource.ClassLoaderWithFlag classLoader =
             getClassLoader();
@@ -106,7 +106,7 @@ public class JavaResource extends AbstractClasspathResource
     @Override
     public int compareTo(Resource another) {
         if (isReference()) {
-            return getCheckedRef().compareTo(another);
+            return getRef().compareTo(another);
         }
         if (another.getClass().equals(getClass())) {
             JavaResource otherjr = (JavaResource) another;
@@ -140,7 +140,7 @@ public class JavaResource extends AbstractClasspathResource
     }
 
     @Override
-    protected JavaResource getCheckedRef() {
-        return (JavaResource) super.getCheckedRef();
+    protected JavaResource getRef() {
+        return getCheckedRef(JavaResource.class);
     }
 }

src/main/org/apache/tools/ant/types/resources/MappedResource.java

@@ -108,7 +108,7 @@ public class MappedResource extends ResourceDecorator {
     @Override
     public String toString() {
         if (isReference()) {
-            return getCheckedRef().toString();
+            return getRef().toString();
         }
         return getName();
     }

src/main/org/apache/tools/ant/types/resources/MappedResourceCollection.java

@@ -127,7 +127,7 @@ public class MappedResourceCollection
     @Override
     public boolean isFilesystemOnly() {
         if (isReference()) {
-            return getCheckedRef().isFilesystemOnly();
+            return getRef().isFilesystemOnly();
         }
         checkInitialized();
         return false;
@@ -139,7 +139,7 @@ public class MappedResourceCollection
     @Override
     public int size() {
         if (isReference()) {
-            return getCheckedRef().size();
+            return getRef().size();
         }
         checkInitialized();
         return cacheCollection().size();
@@ -151,7 +151,7 @@ public class MappedResourceCollection
     @Override
     public Iterator<Resource> iterator() {
         if (isReference()) {
-            return getCheckedRef().iterator();
+            return getRef().iterator();
         }
         checkInitialized();
         return cacheCollection().iterator();
@@ -254,14 +254,13 @@ public class MappedResourceCollection
     @Override
     public String toString() {
         if (isReference()) {
-            return getCheckedRef().toString();
+            return getRef().toString();
         }
         return isEmpty() ? "" : stream().map(Object::toString)
             .collect(Collectors.joining(File.pathSeparator));
     }
 
-    @Override
-    protected MappedResourceCollection getCheckedRef() {
-        return (MappedResourceCollection) super.getCheckedRef();
+    private MappedResourceCollection getRef() {
+        return getCheckedRef(MappedResourceCollection.class);
     }
 }

src/main/org/apache/tools/ant/types/resources/MultiRootFileSet.java

@@ -113,7 +113,7 @@ public class MultiRootFileSet extends AbstractFileSet
     @Override
     public Object clone() {
         if (isReference()) {
-            return getRef(getProject()).clone();
+            return getRef().clone();
         }
         final MultiRootFileSet fs = (MultiRootFileSet) super.clone();
         fs.baseDirs = new ArrayList<>(baseDirs);
@@ -128,7 +128,7 @@ public class MultiRootFileSet extends AbstractFileSet
     @Override
     public Iterator<Resource> iterator() {
         if (isReference()) {
-            return ((MultiRootFileSet) getRef(getProject())).iterator();
+            return getRef().iterator();
         }
         return merge().iterator();
     }
@@ -140,7 +140,7 @@ public class MultiRootFileSet extends AbstractFileSet
     @Override
     public int size() {
         if (isReference()) {
-            return ((MultiRootFileSet) getRef(getProject())).size();
+            return getRef().size();
         }
         return merge().size();
     }
@@ -162,11 +162,15 @@ public class MultiRootFileSet extends AbstractFileSet
     @Override
     public String toString() {
         if (isReference()) {
-            return getRef(getProject()).toString();
+            return getRef().toString();
         }
         return merge().toString();
     }
 
+    private MultiRootFileSet getRef() {
+        return getCheckedRef(MultiRootFileSet.class);
+    }
+
     private synchronized Union merge() {
         if (cache && union != null) {
             return union;
@@ -210,7 +214,7 @@ public class MultiRootFileSet extends AbstractFileSet
 
         @Override
         public Iterator<Resource> iterator() {
-            final DirectoryScanner ds = getDirectoryScanner(getProject());
+            final DirectoryScanner ds = getDirectoryScanner();
             String[] names = type == SetType.file
                 ? ds.getIncludedFiles()
                 : ds.getIncludedDirectories();
@@ -227,7 +231,7 @@ public class MultiRootFileSet extends AbstractFileSet
 
         @Override
         public int size() {
-            final DirectoryScanner ds = getDirectoryScanner(getProject());
+            final DirectoryScanner ds = getDirectoryScanner();
             int count = type == SetType.file
                 ? ds.getIncludedFilesCount()
                 : ds.getIncludedDirsCount();

src/main/org/apache/tools/ant/types/resources/PropertyResource.java

@@ -67,7 +67,7 @@ public class PropertyResource extends Resource {
      */
     public String getValue() {
         if (isReference()) {
-            return getCheckedRef().getValue();
+            return getRef().getValue();
         }
         Project p = getProject();
         return p == null ? null : p.getProperty(getName());
@@ -80,7 +80,7 @@ public class PropertyResource extends Resource {
      */
     public Object getObjectValue() {
         if (isReference()) {
-            return getCheckedRef().getObjectValue();
+            return getRef().getObjectValue();
         }
         Project p = getProject();
         return p == null ? null : PropertyHelper.getProperty(p, getName());
@@ -199,7 +199,7 @@ public class PropertyResource extends Resource {
      */
     protected Resource getReferencedOrProxied() {
         if (isReference()) {
-            return getCheckedRef(Resource.class, "resource");
+            return super.getRef();
         }
         Object o = getObjectValue();
         if (o instanceof Resource) {
@@ -210,7 +210,7 @@ public class PropertyResource extends Resource {
     }
 
     @Override
-    protected PropertyResource getCheckedRef() {
-        return (PropertyResource) super.getCheckedRef();
+    protected PropertyResource getRef() {
+        return getCheckedRef(PropertyResource.class);
     }
 }

src/main/org/apache/tools/ant/types/resources/ResourceDecorator.java

@@ -205,7 +205,7 @@ public abstract class ResourceDecorator extends Resource {
      */
     protected final Resource getResource() {
         if (isReference()) {
-            return getCheckedRef();
+            return getCheckedRef(Resource.class);
         }
         if (resource == null) {
             throw new BuildException("no resource specified");

src/main/org/apache/tools/ant/types/resources/ResourceList.java

@@ -143,7 +143,7 @@ public class ResourceList extends DataType implements ResourceCollection {
     @Override
     public final synchronized Iterator<Resource> iterator() {
         if (isReference()) {
-            return getCheckedRef().iterator();
+            return getRef().iterator();
         }
         return cache().iterator();
     }
@@ -156,7 +156,7 @@ public class ResourceList extends DataType implements ResourceCollection {
     @Override
     public synchronized int size() {
         if (isReference()) {
-            return getCheckedRef().size();
+            return getRef().size();
         }
         return cache().size();
     }
@@ -169,7 +169,7 @@ public class ResourceList extends DataType implements ResourceCollection {
     @Override
     public synchronized boolean isFilesystemOnly() {
         if (isReference()) {
-            return getCheckedRef().isFilesystemOnly();
+            return getRef().isFilesystemOnly();
         }
         return cache().isFilesystemOnly();
     }
@@ -203,9 +203,8 @@ public class ResourceList extends DataType implements ResourceCollection {
         }
     }
 
-    @Override
-    protected ResourceList getCheckedRef() {
-        return (ResourceList) super.getCheckedRef();
+    private ResourceList getRef() {
+        return getCheckedRef(ResourceList.class);
     }
 
     private synchronized ResourceCollection cache() {

src/main/org/apache/tools/ant/types/resources/Resources.java

@@ -219,7 +219,7 @@ public class Resources extends DataType implements ResourceCollection {
     @Override
     public synchronized String toString() {
         if (isReference()) {
-            return getCheckedRef().toString();
+            return getRef().toString();
         }
         validate();
         if (coll == null || coll.isEmpty()) {
@@ -266,7 +266,7 @@ public class Resources extends DataType implements ResourceCollection {
      * @return the referenced ResourceCollection.
      */
     private ResourceCollection getRef() {
-        return getCheckedRef(ResourceCollection.class, "ResourceCollection");
+        return getCheckedRef(ResourceCollection.class);
     }
 
     private synchronized void validate() {

src/main/org/apache/tools/ant/types/resources/Restrict.java

@@ -96,7 +96,7 @@ public class Restrict
     @Override
     public final synchronized Iterator<Resource> iterator() {
         if (isReference()) {
-            return getCheckedRef().iterator();
+            return getRef().iterator();
         }
         dieOnCircularReference();
         return w.iterator();
@@ -109,7 +109,7 @@ public class Restrict
     @Override
     public synchronized int size() {
         if (isReference()) {
-            return getCheckedRef().size();
+            return getRef().size();
         }
         dieOnCircularReference();
         return w.size();
@@ -122,7 +122,7 @@ public class Restrict
     @Override
     public synchronized boolean isFilesystemOnly() {
         if (isReference()) {
-            return getCheckedRef().isFilesystemOnly();
+            return getRef().isFilesystemOnly();
         }
         dieOnCircularReference();
         return w.isFilesystemOnly();
@@ -135,7 +135,7 @@ public class Restrict
     @Override
     public synchronized String toString() {
         if (isReference()) {
-            return getCheckedRef().toString();
+            return getRef().toString();
         }
         dieOnCircularReference();
         return w.toString();
@@ -156,8 +156,7 @@ public class Restrict
         }
     }
 
-    @Override
-    protected Restrict getCheckedRef() {
-        return (Restrict) super.getCheckedRef();
+    private Restrict getRef() {
+        return getCheckedRef(Restrict.class);
     }
 }

src/main/org/apache/tools/ant/types/resources/StringResource.java

@@ -149,7 +149,7 @@ public class StringResource extends Resource {
      */
     @Override
     public synchronized long getSize() {
-        return isReference() ? getCheckedRef().getSize()
+        return isReference() ? getRef().getSize()
             : getContent().length();
     }
 
@@ -161,7 +161,7 @@ public class StringResource extends Resource {
     public synchronized int hashCode() { //NOSONAR
         // super.equals + super.compareTo are consistent with this implementation
         if (isReference()) {
-            return getCheckedRef().hashCode();
+            return getRef().hashCode();
         }
         return super.hashCode() * STRING_MAGIC;
     }
@@ -188,7 +188,7 @@ public class StringResource extends Resource {
     @Override
     public synchronized InputStream getInputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getInputStream();
+            return getRef().getInputStream();
         }
         String content = getContent();
         if (content == null) {
@@ -209,7 +209,7 @@ public class StringResource extends Resource {
     @Override
     public synchronized OutputStream getOutputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getOutputStream();
+            return getRef().getOutputStream();
         }
         if (getValue() != null) {
             throw new ImmutableResourceException();
@@ -238,8 +238,8 @@ public class StringResource extends Resource {
     }
 
     @Override
-    protected StringResource getCheckedRef() {
-        return (StringResource) super.getCheckedRef();
+    protected StringResource getRef() {
+        return getCheckedRef(StringResource.class);
     }
 
     private class StringResourceFilterOutputStream extends FilterOutputStream {

src/main/org/apache/tools/ant/types/resources/TarResource.java

@@ -77,7 +77,7 @@ public class TarResource extends ArchiveResource {
     @Override
     public InputStream getInputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getInputStream();
+            return getRef().getInputStream();
         }
         Resource archive = getArchive();
         final TarInputStream i = new TarInputStream(archive.getInputStream());
@@ -104,7 +104,7 @@ public class TarResource extends ArchiveResource {
     @Override
     public OutputStream getOutputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getOutputStream();
+            return getRef().getOutputStream();
         }
         throw new UnsupportedOperationException(
             "Use the tar task for tar output.");
@@ -115,7 +115,7 @@ public class TarResource extends ArchiveResource {
      */
     public String getUserName() {
         if (isReference()) {
-            return getCheckedRef().getUserName();
+            return getRef().getUserName();
         }
         checkEntry();
         return userName;
@@ -126,7 +126,7 @@ public class TarResource extends ArchiveResource {
      */
     public String getGroup() {
         if (isReference()) {
-            return getCheckedRef().getGroup();
+            return getRef().getGroup();
         }
         checkEntry();
         return groupName;
@@ -138,7 +138,7 @@ public class TarResource extends ArchiveResource {
      */
     public long getLongUid() {
         if (isReference()) {
-            return getCheckedRef().getLongUid();
+            return getRef().getLongUid();
         }
         checkEntry();
         return uid;
@@ -158,7 +158,7 @@ public class TarResource extends ArchiveResource {
      */
     public long getLongGid() {
         if (isReference()) {
-            return getCheckedRef().getLongGid();
+            return getRef().getLongGid();
         }
         checkEntry();
         return gid;
@@ -194,8 +194,8 @@ public class TarResource extends ArchiveResource {
     }
 
     @Override
-    protected TarResource getCheckedRef() {
-        return (TarResource) super.getCheckedRef();
+    protected TarResource getRef() {
+        return getCheckedRef(TarResource.class);
     }
 
     private void setEntry(TarEntry e) {

src/main/org/apache/tools/ant/types/resources/URLResource.java

@@ -143,7 +143,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized URL getURL() {
         if (isReference()) {
-            return ((URLResource) getCheckedRef()).getURL();
+            return getRef().getURL();
         }
         if (url == null) {
             if (baseURL != null) {
@@ -180,7 +180,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized String getName() {
         if (isReference()) {
-            return getCheckedRef().getName();
+            return getRef().getName();
         }
         String name = getURL().getFile();
         return name.isEmpty() ? name : name.substring(1);
@@ -192,7 +192,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized String toString() {
         return isReference()
-            ? getCheckedRef().toString() : String.valueOf(getURL());
+            ? getRef().toString() : String.valueOf(getURL());
     }
 
     /**
@@ -201,7 +201,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized boolean isExists() {
         if (isReference()) {
-            return getCheckedRef().isExists();
+            return getRef().isExists();
         }
         return isExists(false);
     }
@@ -262,7 +262,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized long getLastModified() {
         if (isReference()) {
-            return getCheckedRef().getLastModified();
+            return getRef().getLastModified();
         }
         if (!isExists(false)) {
             return UNKNOWN_DATETIME;
@@ -276,7 +276,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized boolean isDirectory() {
         return isReference()
-            ? getCheckedRef().isDirectory()
+            ? getRef().isDirectory()
             : getName().endsWith("/");
     }
 
@@ -287,7 +287,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized long getSize() {
         if (isReference()) {
-            return getCheckedRef().getSize();
+            return getRef().getSize();
         }
         if (!isExists(false)) {
             return 0L;
@@ -305,7 +305,7 @@ public class URLResource extends Resource implements URLProvider {
             return true;
         }
         if (isReference()) {
-            return getCheckedRef().equals(another);
+            return getRef().equals(another);
         }
         if (another == null || another.getClass() != getClass()) {
             return false;
@@ -322,7 +322,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized int hashCode() {
         if (isReference()) {
-            return getCheckedRef().hashCode();
+            return getRef().hashCode();
         }
         return MAGIC * ((getURL() == null) ? NULL_URL : getURL().hashCode());
     }
@@ -337,7 +337,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized InputStream getInputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getInputStream();
+            return getRef().getInputStream();
         }
         connect();
         try {
@@ -358,7 +358,7 @@ public class URLResource extends Resource implements URLProvider {
      */
     public synchronized OutputStream getOutputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getOutputStream();
+            return getRef().getOutputStream();
         }
         connect();
         try {
@@ -401,6 +401,11 @@ public class URLResource extends Resource implements URLProvider {
         }
     }
 
+    @Override
+    protected URLResource getRef() {
+        return getCheckedRef(URLResource.class);
+    }
+
     /**
      * Closes the URL connection if:
      * - it is opened (i.e. the field conn is not null)

src/main/org/apache/tools/ant/types/resources/Union.java

@@ -82,7 +82,7 @@ public class Union extends BaseResourceCollectionContainer {
      */
     public String[] list() {
         if (isReference()) {
-            return getCheckedRef(Union.class, getDataTypeName()).list();
+            return getRef().list();
         }
         return streamResources().map(Object::toString).toArray(String[]::new);
     }
@@ -93,7 +93,7 @@ public class Union extends BaseResourceCollectionContainer {
      */
     public Resource[] listResources() {
         if (isReference()) {
-            return getCheckedRef(Union.class, getDataTypeName()).listResources();
+            return getRef().listResources();
         }
         return streamResources().toArray(Resource[]::new);
     }
@@ -139,6 +139,10 @@ public class Union extends BaseResourceCollectionContainer {
             .collect(Collectors.toCollection(LinkedHashSet::new));
     }
 
+    private Union getRef() {
+        return getCheckedRef(Union.class);
+    }
+
     private Stream<? extends Resource> streamResources() {
         return streamResources(Function.identity());
     }

src/main/org/apache/tools/ant/types/resources/ZipResource.java

@@ -105,7 +105,7 @@ public class ZipResource extends ArchiveResource {
      */
     public String getEncoding() {
         return isReference()
-            ? ((ZipResource) getCheckedRef()).getEncoding() : encoding;
+            ? getRef().getEncoding() : encoding;
     }
 
     /**
@@ -127,7 +127,7 @@ public class ZipResource extends ArchiveResource {
      */
     public InputStream getInputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getInputStream();
+            return getRef().getInputStream();
         }
         return getZipEntryStream(new ZipFile(getZipfile(), getEncoding()), getName());
     }
@@ -142,7 +142,7 @@ public class ZipResource extends ArchiveResource {
      */
     public OutputStream getOutputStream() throws IOException {
         if (isReference()) {
-            return getCheckedRef().getOutputStream();
+            return getRef().getOutputStream();
         }
         throw new UnsupportedOperationException(
             "Use the zip task for zip output.");
@@ -155,7 +155,7 @@ public class ZipResource extends ArchiveResource {
      */
     public ZipExtraField[] getExtraFields() {
         if (isReference()) {
-            return ((ZipResource) getCheckedRef()).getExtraFields();
+            return getRef().getExtraFields();
         }
         checkEntry();
         if (extras == null) {
@@ -219,6 +219,11 @@ public class ZipResource extends ArchiveResource {
         }
     }
 
+    @Override
+    protected ZipResource getRef() {
+        return getCheckedRef(ZipResource.class);
+    }
+
     private void setEntry(ZipEntry e) {
         if (e == null) {
             setExists(false);

src/main/org/apache/tools/ant/types/resources/comparators/DelegatedResourceComparator.java

@@ -54,7 +54,7 @@ public class DelegatedResourceComparator extends ResourceComparator {
 
     /**
      * Equality method based on the vector of resources,
-     * or if a reference, the referredto object.
+     * or if a reference, the referred to object.
      * @param o the object to check against.
      * @return true if there is equality.
      */
@@ -64,7 +64,7 @@ public class DelegatedResourceComparator extends ResourceComparator {
             return true;
         }
         if (isReference()) {
-            return getCheckedRef().equals(o);
+            return getCheckedRef(DelegatedResourceComparator.class).equals(o);
         }
         if (o instanceof DelegatedResourceComparator) {
             List<ResourceComparator> ov = ((DelegatedResourceComparator) o).resourceComparators;
@@ -80,7 +80,7 @@ public class DelegatedResourceComparator extends ResourceComparator {
     @Override
     public synchronized int hashCode() {
         if (isReference()) {
-            return getCheckedRef().hashCode();
+            return getCheckedRef(DelegatedResourceComparator.class).hashCode();
         }
         return resourceComparators == null ? 0 : resourceComparators.hashCode();
     }

src/main/org/apache/tools/ant/types/resources/comparators/ResourceComparator.java

@@ -39,7 +39,7 @@ public abstract class ResourceComparator extends DataType implements Comparator<
     @Override
     public final int compare(Resource foo, Resource bar) {
         dieOnCircularReference();
-        ResourceComparator c = isReference() ? getCheckedRef() : this;
+        ResourceComparator c = isReference() ? getRef() : this;
         return c.resourceCompare(foo, bar);
     }
 
@@ -51,7 +51,7 @@ public abstract class ResourceComparator extends DataType implements Comparator<
     @Override
     public boolean equals(Object o) {
         if (isReference()) {
-            return getCheckedRef().equals(o);
+            return getRef().equals(o);
         }
         return o != null && (o == this || o.getClass().equals(getClass()));
     }
@@ -63,7 +63,7 @@ public abstract class ResourceComparator extends DataType implements Comparator<
     @Override
     public synchronized int hashCode() {
         if (isReference()) {
-            return getCheckedRef().hashCode();
+            return getRef().hashCode();
         }
         return getClass().hashCode();
     }
@@ -77,8 +77,7 @@ public abstract class ResourceComparator extends DataType implements Comparator<
      */
     protected abstract int resourceCompare(Resource foo, Resource bar);
 
-    @Override
-    protected ResourceComparator getCheckedRef() {
-        return (ResourceComparator) super.getCheckedRef();
+    private ResourceComparator getRef() {
+        return getCheckedRef(ResourceComparator.class);
     }
 }

src/main/org/apache/tools/ant/types/resources/selectors/Compare.java

@@ -100,7 +100,7 @@ public class Compare extends DataType implements ResourceSelector {
     /** {@inheritDoc} */
     public synchronized boolean isSelected(Resource r) {
         if (isReference()) {
-            return ((ResourceSelector) getCheckedRef()).isSelected(r);
+            return getRef().isSelected(r);
         }
         if (control == null) {
             throw oneControl();
@@ -140,6 +140,10 @@ public class Compare extends DataType implements ResourceSelector {
         }
     }
 
+    private ResourceSelector getRef() {
+        return getCheckedRef(ResourceSelector.class);
+    }
+
     private BuildException oneControl() {
         return new BuildException("%s the <control> element should be specified exactly once.",
                 super.toString());

src/main/org/apache/tools/ant/types/resources/selectors/ResourceSelectorContainer.java

@@ -72,7 +72,7 @@ public class ResourceSelectorContainer extends DataType {
      */
     public boolean hasSelectors() {
         if (isReference()) {
-            return getCheckedRef().hasSelectors();
+            return getRef().hasSelectors();
         }
         dieOnCircularReference();
         return !resourceSelectors.isEmpty();
@@ -84,7 +84,7 @@ public class ResourceSelectorContainer extends DataType {
      */
     public int selectorCount() {
         if (isReference()) {
-            return getCheckedRef().selectorCount();
+            return getRef().selectorCount();
         }
         dieOnCircularReference();
         return resourceSelectors.size();
@@ -96,7 +96,7 @@ public class ResourceSelectorContainer extends DataType {
      */
     public Iterator<ResourceSelector> getSelectors() {
         if (isReference()) {
-            return getCheckedRef().getSelectors();
+            return getRef().getSelectors();
         }
         return getResourceSelectors().iterator();
     }
@@ -107,7 +107,7 @@ public class ResourceSelectorContainer extends DataType {
      */
     public List<ResourceSelector> getResourceSelectors() {
         if (isReference()) {
-            return getCheckedRef().getResourceSelectors();
+            return getRef().getResourceSelectors();
         }
         dieOnCircularReference();
         return Collections.unmodifiableList(resourceSelectors);
@@ -136,8 +136,7 @@ public class ResourceSelectorContainer extends DataType {
         }
     }
 
-    @Override
-    protected ResourceSelectorContainer getCheckedRef() {
-        return (ResourceSelectorContainer) super.getCheckedRef();
+    private ResourceSelectorContainer getRef() {
+        return getCheckedRef(ResourceSelectorContainer.class);
     }
 }

src/main/org/apache/tools/ant/types/selectors/AbstractSelectorContainer.java

@@ -50,7 +50,7 @@ public abstract class AbstractSelectorContainer extends DataType
     @Override
     public boolean hasSelectors() {
         if (isReference()) {
-            return getCheckedRef().hasSelectors();
+            return getRef().hasSelectors();
         }
         dieOnCircularReference();
         return !selectorsList.isEmpty();
@@ -62,7 +62,7 @@ public abstract class AbstractSelectorContainer extends DataType
      */
     public int selectorCount() {
         if (isReference()) {
-            return getCheckedRef().selectorCount();
+            return getRef().selectorCount();
         }
         dieOnCircularReference();
         return selectorsList.size();
@@ -75,8 +75,7 @@ public abstract class AbstractSelectorContainer extends DataType
      */
     public FileSelector[] getSelectors(Project p) {
         if (isReference()) {
-            return getCheckedRef(AbstractSelectorContainer.class,
-                getDataTypeName(), p).getSelectors(p);
+            return getRef(p).getSelectors(p);
         }
         dieOnCircularReference(p);
         return selectorsList.toArray(new FileSelector[selectorsList.size()]);
@@ -88,7 +87,7 @@ public abstract class AbstractSelectorContainer extends DataType
      */
     public Enumeration<FileSelector> selectorElements() {
         if (isReference()) {
-            return getCheckedRef().selectorElements();
+            return getRef().selectorElements();
         }
         dieOnCircularReference();
         return Collections.enumeration(selectorsList);
@@ -137,7 +136,7 @@ public abstract class AbstractSelectorContainer extends DataType
      */
     public void validate() {
         if (isReference()) {
-            getCheckedRef().validate();
+            getRef().validate();
         }
         dieOnCircularReference();
         selectorsList.stream().filter(BaseSelector.class::isInstance)
@@ -367,7 +366,7 @@ public abstract class AbstractSelectorContainer extends DataType
 
     public synchronized Object clone() {
         if (isReference()) {
-            return getCheckedRef().clone();
+            return getRef().clone();
         }
         try {
             AbstractSelectorContainer sc =
@@ -379,9 +378,13 @@ public abstract class AbstractSelectorContainer extends DataType
         }
     }
 
-    @Override
-    protected AbstractSelectorContainer getCheckedRef() {
-        return (AbstractSelectorContainer) super.getCheckedRef();
+
+    private AbstractSelectorContainer getRef(Project p) {
+        return getCheckedRef(AbstractSelectorContainer.class, getDataTypeName(), p);
+    }
+
+    private AbstractSelectorContainer getRef() {
+        return getCheckedRef(AbstractSelectorContainer.class);
     }
 
 }

src/main/org/apache/tools/ant/types/selectors/BaseSelector.java

@@ -80,7 +80,7 @@ public abstract class BaseSelector extends DataType implements FileSelector {
      */
     public void verifySettings() {
         if (isReference()) {
-            getCheckedRef().verifySettings();
+            getRef().verifySettings();
         }
     }
 
@@ -114,9 +114,8 @@ public abstract class BaseSelector extends DataType implements FileSelector {
     public abstract boolean isSelected(File basedir, String filename,
                                        File file);
 
-    @Override
-    protected BaseSelector getCheckedRef() {
-        return (BaseSelector) super.getCheckedRef();
+    private BaseSelector getRef() {
+        return getCheckedRef(BaseSelector.class);
     }
 }
 

src/main/org/apache/tools/ant/types/selectors/SelectSelector.java

@@ -66,7 +66,7 @@ public class SelectSelector extends BaseSelectorContainer {
      * referenced Selector.
      */
     private SelectSelector getRef() {
-        return getCheckedRef(this.getClass(), "SelectSelector");
+        return getCheckedRef(SelectSelector.class);
     }
 
     /**

src/tests/junit/org/apache/tools/ant/taskdefs/TarTest.java

@@ -182,5 +182,8 @@ public class TarTest {
                 FileUtilities.getFileContents(new File(buildRule.getProject().getProperty("output"), "untar/asf-logo.gif.gz")));
     }
 
-
+    @Test
+    public void testtestTarFilesetWithReference() {
+        buildRule.executeTarget("testTarFilesetWithReference");
+    }
 }