public void addCustomParameter(CustomParameter customParameter){
  if (customParameter == null) {
    throw new NullPointerException("Null custom parameter");
  }
  customParameters.add(customParameter);
}

public void addCustomParameter ( CustomParameter customParameter ) { if ( customParameter == null ) { throw new NullPointerException ( "Null custom parameter" ) ; } customParameters . add ( customParameter ) ; }
adds a new customparameter .
