fix NPE when running inside a container that puts non-String values inside the system properties

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@671018 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -73,6 +73,9 @@ Fixed bugs:
    within messageLogged while a different thread also accessed one.
    Bugzilla report 45194
 
+ * Handle null result of system getProperty() in CommandlineJava.
+   Similar to Bugzilla report 42334.
+
 Other changes:
 --------------
 

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

@@ -140,7 +140,10 @@ public class CommandlineJava implements Cloneable {
                 Properties p = new Properties();
                 for (Enumeration e = sys.propertyNames(); e.hasMoreElements();) {
                     String name = (String) e.nextElement();
-                    p.put(name, sys.getProperty(name));
+                    String value = sys.getProperty(name);
+                    if (name != null && value != null) {
+                        p.put(name, value);
+                    }
                 }
                 p.putAll(mergePropertySets());
                 for (Enumeration e = variables.elements(); e.hasMoreElements();) {