class_docstr: Metaclass for ResolverOp.
  
  Features:
  1. ResolverOp cannot be instantiated directly. Calling ResolverOp() returns
     OpNode instance which is used for function tracing. Instead _ResolverOpMeta
     exposes create() classmethod to actually create a ResolverOp isntance.
  2. _ResolverOpMeta is aware of Property, and keyword argument values
     given from the ResolverOp invocation is validated without creating a
     ResolverOp instance.
  3. It inherits ABCMeta, so @abstractmethod works.
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code: def return_data_type(cls) -> DataType:
      return cls._return_data_type
  
imports: from __future__ import annotations
  import abc
  from typing import Any, Generic, Literal, Mapping, Optional, Sequence, Set, Type, TypeVar, Union
  import attr
  from tfx import types
  from tfx.proto.orchestration import pipeline_pb2
  from tfx.utils import json_utils
  from tfx.utils import typing_utils
  import ml_metadata
label_desc: Use image node_id 5 for calling the _ResolverOpMeta obj's underlying member method code with example usage: obj.return_data_type(cls) and returns: cls