[NETBEANS-6970] Disabling the multi source handling by default.

java/java.file.launcher/src/org/netbeans/modules/java/file/launcher/queries/MultiSourceRootProvider.java

@@ -69,7 +69,7 @@
 })
 public class MultiSourceRootProvider implements ClassPathProvider {
 
-    public static boolean DISABLE_MULTI_SOURCE_ROOT = false;
+    public static boolean DISABLE_MULTI_SOURCE_ROOT = Boolean.getBoolean("java.disable.multi.source.root");
 
     //TODO: the cache will probably be never cleared, as the ClassPath/value refers to the key(?)
     private Map<FileObject, ClassPath> file2SourceCP = new WeakHashMap<>();