Gradle: Add group and description to task defined in custom plugin

build.gradle

class Greeting implements Plugin<Project> {
    void apply(Project target) {
        def helloTask = target.task('hello', type: HelloTask)
        helloTask .group = 'greeting'
        helloTask .description = 'Say hello.'
        target.task('hi', type: HiTask){
            group = 'greeting'
            description = 'Say hi.'
        }
    }
}

class HelloTask extends DefaultTask {
    @TaskAction
    def greet() {
        println 'hello'
    }
}


class HiTask extends DefaultTask {
    @TaskAction
    def greet() {
        println 'hi'
    }
}

apply plugin: Greeting