#data
interface A {
  setlike <C?>;
};
#parsed
{
  "definitions": [
    {
      "definition_type": "interface",
      "name": "A",
      "index": 0,
      "members": [
        {
          "index": 16,
          "member_type": "setlike",
          "type1": {
            "type_name": "C",
            "type_nullable": 1
          }
        }
      ]
    }
  ]
}

#data
interface A {
  readonly setlike <Promise<C>>;
};
#parsed
{
  "definitions": [
    {
      "definition_type": "interface",
      "name": "A",
      "index": 0,
      "members": [
        {
          "index": 16,
          "member_type": "setlike",
          "readonly": 1,
          "type1": {
            "type_parameterized": {
              "type_name": "C",
              "type_outer": "Promise"
            }
          }
        }
      ]
    }
  ]
}