properly check return value of mapFileName

https://bz.apache.org/bugzilla/show_bug.cgi?id=62076

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

@@ -788,6 +788,9 @@ public class Copy extends Task {
         for (int i = 0; i < toCopy.length; i++) {
             final File src = new File(fromDir, toCopy[i]);
             final String[] mappedFiles = mapper.mapFileName(toCopy[i]);
+            if (mappedFiles == null || mappedFiles.length == 0) {
+                continue;
+            }
 
             if (!enableMultipleMappings) {
                 map.put(src.getAbsolutePath(),
@@ -836,7 +839,7 @@ public class Copy extends Task {
         }
         for (int i = 0; i < toCopy.length; i++) {
             final String[] mappedFiles = mapper.mapFileName(toCopy[i].getName());
-            if (mappedFiles == null) {
+            if (mappedFiles == null || mappedFiles.length == 0) {
                 throw new BuildException("Can't copy a resource without a"
                         + " name if the mapper doesn't"
                         + " provide one.");

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

@@ -182,6 +182,9 @@ public class CopyPath extends Task {
             String sourceFileName = sourceFiles[sources];
             File sourceFile = new File(sourceFileName);
             String[] toFiles = (String[]) mapper.mapFileName(sourceFileName);
+            if (toFiles == null) {
+                continue;
+            }
 
             for (int i = 0; i < toFiles.length; i++) {
                 String destFileName = toFiles[i];

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

@@ -709,6 +709,9 @@ public class Rmic extends MatchingTask {
         String classFileName = classname.replace('.', File.separatorChar)
             + ".class";
         String[] generatedFiles = adapter.getMapper().mapFileName(classFileName);
+        if (generatedFiles == null) {
+            return;
+        }
 
         for (int i = 0; i < generatedFiles.length; i++) {
             final String generatedFile = generatedFiles[i];

src/main/org/apache/tools/ant/taskdefs/optional/Native2Ascii.java

@@ -255,7 +255,10 @@ public class Native2Ascii extends MatchingTask {
             + (count != 1 ? "s" : "") + " from ";
         log(message + srcDir + " to " + destDir);
         for (int i = 0; i < files.length; i++) {
-            convert(files[i], m.mapFileName(files[i])[0]);
+            String[] dest = m.mapFileName(files[i]);
+            if (dest != null && dest.length > 0) {
+                convert(files[i], dest[0]);
+            }
         }
     }