fall back to java.vm.version if java.runtime.version cannot be found

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@802486 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -141,8 +141,8 @@ Changes that could break older environments:
    set failOnError to false.
    Bugzilla Report 47362.
 
- * Ant now uses the java.runtime.version instead of java.vm.version
-   system property for the Created-By Manifest attribute.
+ * Ant now prefers the java.runtime.version system property over
+   java.vm.version for the Created-By Manifest attribute.
    Bugzilla Report 47632.
 
 Fixed bugs:

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

@@ -745,8 +745,12 @@ public class Manifest {
             try {
                 insr = new InputStreamReader(in, "UTF-8");
                 Manifest defaultManifest = new Manifest(insr);
+                String version = System.getProperty("java.runtime.version");
+                if (version == null) {
+                    version = System.getProperty("java.vm.version");
+                }
                 Attribute createdBy = new Attribute("Created-By",
-                    System.getProperty("java.runtime.version") + " ("
+                    version + " ("
                     + System.getProperty("java.vm.vendor") + ")");
                 defaultManifest.getMainSection().storeAttribute(createdBy);
                 return defaultManifest;