code: def testOneofFields(self):
      message = json_format_proto3_pb2.TestOneof()
      # Always print does not affect oneof fields.
      self.assertEqual(json_format.MessageToJson(message, True), "{}")
      message.oneof_int32_value = 0
      self.assertEqual(
          json_format.MessageToJson(message, True),
          "{\n" '  "oneofInt32Value": 0\n' "}",
      )
      parsed_message = json_format_proto3_pb2.TestOneof()
      self.CheckParseBack(message, parsed_message)
  
imports: import json
  import math
  import sys
  from google.protobuf import any_pb2
  from google.protobuf import duration_pb2
  from google.protobuf import field_mask_pb2
  from google.protobuf import struct_pb2
  from google.protobuf import timestamp_pb2
  from google.protobuf import wrappers_pb2
  from google.protobuf.internal import well_known_types
  from google.protobuf import json_format
  from google.protobuf.util import json_format_proto3_pb2
label_desc: Use image node_id 8 for calling the JsonFormatTest obj's underlying member method code with example usage: obj.testOneofFields() without return types