gradle add file to existing war jar

build.gradle

task addToWar(type: Jar) {
    destinationDir = file('dist')
    archiveName = 'drools-guvnor.war' 
    from zipTree('ss/drools-guvnor.war')
    from(file("ss/RRR.txt")) {
        into ('META-INF')
    }
}