Try to fix compilation error (see https://bugs.openjdk.java.net/browse/JDK-8212636 workaround)

jme3-core/src/com/jme3/gde/core/util/PropertyUtils.java

@@ -45,7 +45,7 @@ public class PropertyUtils {
 
     public static PropertyDescriptor getPropertyDescriptor(Class c, Field field) {
         try {
-            PropertyDescriptor prop = new PropertyDescriptor(field.getName(), c);
+            PropertyDescriptor prop = new PropertyDescriptor((String)field.getName(), c);
 
             prop.setDisplayName(splitCamelCase(field.getName()));