Clone bounds arrays in WildcardTypeImpl, as done for arrays in other type implementations

Author: ljacqu

src/main/java/ch/jalu/typeresolver/typeimpl/WildcardTypeImpl.java

@@ -58,12 +58,12 @@ public static WildcardType newUnboundedWildcard() {
 
     @Override
     public Type[] getUpperBounds() {
-        return upperBounds;
+        return upperBounds.clone();
     }
 
     @Override
     public Type[] getLowerBounds() {
-        return lowerBounds;
+        return lowerBounds.clone();
     }
 
     @Override