message: Remove accessing `Graph._collections` via the protected member in tensorflow/python/framework/function.py.
diff: @@ -389,13 +389,9 @@ class _DefinedFunction(object):
  variable_keys.extend(ops.GraphKeys._VARIABLE_COLLECTIONS) # pylint: disable=protected-access
  variable_keys.append(vs._VARSTORE_KEY) # pylint: disable=protected-access
  - collections_ref = {}
  - parent_collections_ref = ops.get_default_graph()._collections # pylint: disable=protected-access
  - for key in variable_keys:
  - if key not in parent_collections_ref:
  - parent_collections_ref[key] = collections_ref[key] = []
  - else:
  - collections_ref[key] = parent_collections_ref[key]
  + parent_graph = ops.get_default_graph()
  + collections_ref = {
  + key: parent_graph.get_collection_ref(key) for key in variable_keys}
  temp_graph = func_graph_from_py_func(
  self._func,
  