Fix the inefficient use of keySet iterator with entrySet iterator.

The current source code accesses the key and value of a Hashtable entry, using a key that is retrieved from a keySet iterator.
It is more efficient to use an iterator on the entrySet of the Hashtable, to avoid the Map.get(key) lookup.

src/main/org/apache/tools/ant/filters/ReplaceTokens.java

@@ -23,6 +23,7 @@ import java.io.InputStream;
 import java.io.Reader;
 import java.util.Enumeration;
 import java.util.Hashtable;
+import java.util.Map;
 import java.util.Properties;
 import java.util.SortedMap;
 import java.util.TreeMap;
@@ -116,8 +117,8 @@ public final class ReplaceTokens
 
         if (!resolvedTokensBuilt) {
             // build the resolved tokens tree map.
-            for (String key : hash.keySet()) {
-                resolvedTokens.put(beginToken + key + endToken, hash.get(key));
+            for (Map.Entry<String, String> entry : hash.entrySet()) {
+                resolvedTokens.put(beginToken + entry.getKey() + endToken, entry.getValue());
             }
             resolvedTokensBuilt = true;
         }