ArrayAttr classes_attr = op->getAttrOfType<ArrayAttr>(kClassAttr);
  if (!classes_attr) {
    // Attempt to parse "_class" from the IdentityOp that follows VariableV2.
    // For read-only reference variables, IdentityOp should be the only user of
    // VariableV2.
    auto identity_op = op->getUsers().begin();
    classes_attr = identity_op->getAttrOfType<ArrayAttr>(kClassAttr);
    if (!classes_attr) {