code: public void setMandatory(final boolean mandatory, final String message) {
  		setFlag(ComponentModel.MANDATORY_FLAG, mandatory);
  		getOrCreateComponentModel().errorMessage = message;
  	}
docs: Set whether or not this field set is mandatory, and customise the error message that will be displayed.
  
  @param mandatory true for mandatory, false for optional.
  @param message the message to display to the user on mandatory validation failure.