Is it possible to call one custom keyword function from another Custom keywords from katalon Automation Tool?

Question

I am trying to call method from one custom keywords to another Custom keywords functions

But i am getting below error,

05-30-2018 02:59:02 PM - [START] - Start action : mandatoryfield_Validation.Mandatoryfieldvalidation.textfieldvalidation 05-30-2018 02:59:02 PM - [INFO] - Finding Test Object with id 'Object Repository/HelpDeskModule/Master/Team/Page_eFACiLiTY/input_Txt_Code' 05-30-2018 02:59:02 PM - [ERROR] - No such property: CustomKeywords for class: mandatoryfield_Validation.Mandatoryfieldvalidation 05-30-2018 02:59:02 PM - [END] - End action : mandatoryfield_Validation.Mandatoryfieldvalidation.textfieldvalidation 05-30-2018 02:59:02 PM - [ERROR] - Test Cases/HelpDeskModule/Master/Team_/Team FAILED because (of) Variable 'CustomKeywords' is not defined for test case.

please find the code below

public class Mandatoryfieldvalidation {
//<!--Initializing object-->

private static Connection connection = null;
private static  String columntype;
private static int num;
private static int datatypevalue
def driver = DF.getWebDriver()
KeywordLogger logger = new KeywordLogger()
JavascriptExecutor js = ((driver) as JavascriptExecutor)
//Method for validating textfield
@Keyword
def void textfieldvalidation()
{
CustomKeywords.'alerthandling.verifyalertpresent.verifyalert'()

}
}