Fix javadoc (cherry-pick master)

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

@@ -204,6 +204,8 @@ public class PatternSet extends DataType implements Cloneable {
         /**
          * Encoding to use when reading the file, defaults to the platform's default
          * encoding.
+         *
+         * @return the encoding name
          */
         public final String getEncoding() {
             return encoding;