@classmethod
  def _synthetic_runtime_target(cls, buildgraph):
    """Insert synthetic target for scala runtime into the buildgraph
    :param pants.build_graph.build_graph.BuildGraph buildgraph: buildgraph object
    :return pants.build_graph.address.Address:
    """
    # If a custom runtime is specified return it instead of synthetic target
    # This will pull in user defined scala-library defs
    custom_runtime_spec = ScalaPlatform.global_instance().runtime[0]

    if ScalaPlatform.global_instance().version == 'custom':
      return custom_runtime_spec