How to make gradle / gradlew pass args to java class?

build.md

gradle execute -DmainClass=com.my.package.MainClassX -Dexec.args="arg1 arg2 arg3"

task execute (type:JavaExec) {
    main = System.getProperty("mainClass")
    classpath = sourceSets.main.runtimeClasspath 
    systemProperties System.getProperties()
    args System.getProperty("exec.args").split()    
}