code: public void setAuthToken(String authToken){
          if (authToken != null && authToken.length() != AUTH_TOKEN_LENGTH){            
              throw new IllegalArgumentException(authToken+" is not "+AUTH_TOKEN_LENGTH+" characters long.");
          }
          setParameter(AUTH_TOKEN, authToken);
      }
docs: Set the {@value #AUTH_TOKEN_LENGTH} character authorization key used to authenticate the API request.
  @param authToken the authorization key to set.  A null value will remove this parameter