code: function WebPushDataValidator(data) {
    MessagingUserStatus.call(this, 'webpush validator');
  
    // Ensure required data is available
    if (!data.message || typeof data.message === 'undefined') {
      this.state.code = this.StatusCodes.MISSING;
      this.state.message = '`message` key required.';
  
    } else if (!data.url || typeof data.url === 'undefined') {
      this.state.code = this.StatusCodes.MISSING;
      this.state.message = '`url` key required.';
  
    } else {
      // Input data is valid
      this.state.code = this.StatusCodes.VALID;
      this.state.message = 'Ok';
    }
  }
docs: /*
  WebPush validation
  
  @param data         The content of the web push notification