Missing Method Exception

Getting Below error 

groovy.lang.MissingMethodException: No signature of method: com.eviware.soapui.impl.wsdl.WsdlTestCasePro.setPropertyValue() is applicable for argument types: (java.lang.String, java.lang.Long) values: [gettime, 1543510643941] Possible solutions: setPropertyValue(java.lang.String, java.lang.String), getPropertyValue(java.lang.String) error at line: 18

 

Code : 

import com.eviware.soapui.model.testsuite.TestStepResult.TestStepStatus
import com.eviware.soapui.model.testsuite.TestRunner.Status
import com.eviware.soapui.SoapUI

// This Piece will get the current time in milliseconds and add 60 seconds

def m1 = System.currentTimeMillis()
//log.info m1

def m2 = new Date()
//log.info m2.getTime()

def newt = m1 + 60 * 60 * 1000

log.info newt

testRunner.testCase.setPropertyValue("gettime", newt)