code: public void setMetaClassCreationHandle(MetaClassCreationHandle handle) {
          if(handle == null) throw new IllegalArgumentException("Cannot set MetaClassCreationHandle to null value!");
          ClassInfo.clearModifiedExpandos();
          handle.setDisableCustomMetaClassLookup(metaClassCreationHandle.isDisableCustomMetaClassLookup());
          metaClassCreationHandle = handle;
      }
docs: Sets a handle internally used to create MetaClass implementations.
  When replacing the handle with a custom version, you should
  reuse the old handle to keep custom logic and to use the
  default logic as fall back.
  WARNING: experimental code, likely to change soon
  @param handle the handle