refactor for java package split

Author: jenschude

commercetools/commercetools-sdk-java-importapi/src/main/java/com/commercetools/importapi/json/ErrorAttributeDeserializer.java

@@ -178,6 +178,11 @@ public ReferenceType getTypeId() {
             @Override
             public void setKey(String key) {
             }
+
+            @Override
+            public KeyReference copyDeep() {
+                return null;
+            }
         };
     }
 }