Javadoc clarification for Resource.getLastModified.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@582364 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -172,10 +172,11 @@ public class Resource extends DataType implements Cloneable, Comparable, Resourc
     }
 
     /**
-     * Tells the modification time in milliseconds since 01.01.1970 .
+     * Tells the modification time in milliseconds since 01.01.1970 (the "epoch").
      *
-     * @return 0 if the resource does not exist to mirror the behavior
-     * of {@link java.io.File File}.
+     * @return the modification time, if that is meaningful (e.g. for a file resource which exists);
+     *         0 if the resource does not exist, to mirror the behavior of {@link java.io.File#lastModified};
+     *         or 0 if the notion of modification time is meaningless for this class of resource (e.g. an inline string)
      */
     public long getLastModified() {
         if (isReference()) {