Gradle Jar task not working after upgrade from 0.9.2 to 2.1 version

Hi, i am upgrading from 0.9.2 to 2.1 version but the jar task is not working, below is my gradle.build file -

apply plugin: ‘java’

task testJar(type: Jar) {

archiveName = ‘abc.jar’

}

The same code is working with gradle version 0.9.2 but not with gradle version 1.5 or gradle version 2.1

Please check and let me know, if i need to change this in order to make this work with 1.5 or 2.1 gradle versions.