Mapping Cognito attributes to AVP Set type

Is it possible to map Cognito attributes to AVP Set type in the schema as below with somelist, where the somelist custom attribute in the cognito userpool is a comma separated list of values.

    "User": {
      "shape": {
        "type": "Record",
        "attributes": {
          "custom": {
            "attributes": {
              "somelist": {
                "type": "Set",
                "element": {
                  "type": "String"
                }
              }
            },
            "type": "Record"
          }
        }
      }
    }