def _process_return_value(self) -> Parameter:
    """Returns a Parameter object representing the return type."""
    responses = self._operation.responses or {}
    # Default to Any if no 2xx response or if schema is missing
    return_schema = Schema(type='Any')

    # Take the 20x response with the smallest response code.
    valid_codes = list(
        filter(lambda k: k.startswith('2'), list(responses.keys()))
    )
    min_20x_status_code = min(valid_codes) if valid_codes else None

    if min_20x_status_code and responses[min_20x_status_code].content:
      content = responses[min_20x_status_code].content
      for mime_type in content:
        if content[mime_type].schema_:
          return_schema = content[mime_type].schema_
          break

    self._return_value = ApiParameter(
        original_name='',
        param_location='',
        param_schema=return_schema,
    )
Returns a Parameter object representing the return type.
src/google/adk/tools/openapi_tool/openapi_spec_parser/operation_parser.py