I am getting "Filled_Save FAILED because (of) (Stack trace: java.lang.ClassNotFoundException: helper" this error, please suggest how to remove this error

Hello,

I have created custom keyword to Create Global Variables on the fly using the code provided on “https://docs.katalon.com/katalon-studio/docs/create-global-variables-on-the-fly.html”.

Code is as below;
@Keyword
void addGlobalVariable(String name, def value) {
GroovyShell shell1 = new GroovyShell()
MetaClass mc = shell1.evaluate(“internal.GlobalVariable”).metaClass
String getterName = “get” + name.capitalize()
mc.‘static’."$getterName" = { → return value }
mc.‘static’."$name" = value

**Then in the script code, you can use GlobalVariable.VarName**
CustomKeywords.'helper.addGlobalVariable'('localURL', 'katalon.com')
println GlobalVariable.localURL

But I am getting below error:
 Test Cases/CAR/03. Create CAR/38997-CAR_Background and Define_Mandatory Fields - Filled_Save FAILED because (of) (Stack trace: java.lang.ClassNotFoundException: helper
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:677)
	at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:787)
	at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:775)
	at com.kms.katalon.core.main.CustomKeywordDelegatingMetaClass.getCustomKeywordClassAndSetMetaClass(CustomKeywordDelegatingMetaClass.java:96)
	at com.kms.katalon.core.main.CustomKeywordDelegatingMetaClass.invokeStaticMethod(CustomKeywordDelegatingMetaClass.java:41)
	at org.codehaus.groovy.runtime.callsite.StaticMetaClassSite.call(StaticMetaClassSite.java:53)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:133)
	at Script1545988573948.run(Script1545988573948.groovy:301)
	at com.kms.katalon.core.main.ScriptEngine.run(ScriptEngine.java:183)
	at com.kms.katalon.core.main.ScriptEngine.runScriptAsRawText(ScriptEngine.java:108)
	at com.kms.katalon.core.main.TestCaseExecutor.runScript(TestCaseExecutor.java:294)
	at com.kms.katalon.core.main.TestCaseExecutor.doExecute(TestCaseExecutor.java:285)
	at com.kms.katalon.core.main.TestCaseExecutor.processExecutionPhase(TestCaseExecutor.java:264)
	at com.kms.katalon.core.main.TestCaseExecutor.accessMainPhase(TestCaseExecutor.java:256)
	at com.kms.katalon.core.main.TestCaseExecutor.execute(TestCaseExecutor.java:200)
	at com.kms.katalon.core.main.TestCaseMain.runTestCase(TestCaseMain.java:99)
	at com.kms.katalon.core.main.TestCaseMain.runTestCase(TestCaseMain.java:90)
	at com.kms.katalon.core.main.TestCaseMain$runTestCase$0.call(Unknown Source)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:149)
	at TempTestCase1546406581298.run(TempTestCase1546406581298.groovy:22)
	at groovy.lang.GroovyShell.runScriptOrMainOrTestOrRunnable(GroovyShell.java:263)
	at groovy.lang.GroovyShell.run(GroovyShell.java:518)
	at groovy.lang.GroovyShell.run(GroovyShell.java:507)
	at groovy.ui.GroovyMain.processOnce(GroovyMain.java:653)
	at groovy.ui.GroovyMain.run(GroovyMain.java:384)
	at groovy.ui.GroovyMain.process(GroovyMain.java:370)
	at groovy.ui.GroovyMain.processArgs(GroovyMain.java:129)
	at groovy.ui.GroovyMain.main(GroovyMain.java:109)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.codehaus.groovy.tools.GroovyStarter.rootLoader(GroovyStarter.java:109)
	at org.codehaus.groovy.tools.GroovyStarter.main(GroovyStarter.java:131)


Please suggest this to remove this error

‘helper’ is the class containing the keyword. Could you double check that. if you name the class differently, that line of code should be changed too.