AssetManager ImplHandler: synchronized access in clearCache()

jme3-core/src/main/java/com/jme3/asset/ImplHandler.java

@@ -204,10 +204,12 @@ public class ImplHandler {
     
     public void clearCache(){
         // The iterator of the values collection is thread safe
+        synchronized (classToCacheMap) {
             for (AssetCache cache : classToCacheMap.values()){
                 cache.clearCache();
             }
         }
+    }
     
     public <T extends AssetCache> T getCache(Class<T> cacheClass) {
         if (cacheClass == null) {