code: public Query addCustomUrlParam(String key, String value) {
      customUrlParams.add(new CustomUrlParam().setKey(key).setValue(value));
      return this;
    }
docs: <code>
  Sets any additional parameters that can be used to trigger rules.
  Takes a name and a value.
  
  JSON Reference:
  
  Custom URL parameters separated by ~ in the form:
  
  { "customUrlParams": [ { "key": "region", "value": "east" } ] }
  
  </code>
  
  @param key
  The parameter key
  @param value
  The parameter value