question: returns an empty operationcallback , type-safe . concode_field_sep OperationCallback EMPTY_CALLBACK concode_field_sep void calledOperationSucceeded concode_elem_sep int scheduleEmptyOperation concode_elem_sep void calledOperationFailed concode_elem_sep Operation<TResult> createEmptyOperation concode_elem_sep Operation<TResult> createEmptyOperationResult
target: OperationCallback < TResult > function ( ) { return Operations . EMPTY_CALLBACK ; }