code: protected void init() {
  		_metaDataRegistry = new DefaultMetaDataRegistry();
      	_selectorResolver = new SelectorResolver();
          _selectorResolver.getBaseSelector().setEntityConfigurationRegistry( new DefaultEntityConfigurationRegistry() );
          _metaDataRegistry.setCoreSelector( this._selectorResolver.getBaseSelector() );
          _metaDataRegistry.setRootMetaDataUrl( "/metadata/" );
  	}
docs: there are cases where a user might want to override meta data registry,
  selector resolver and/or CoreSelector implementations. This would be the
  place to do it, since we have complex dependencies for those objects, and
  we need those objects set up before other setters are called.