allprojects {
    task hello {
        doLast { task ->
            println "I'm $task.project.name"
        }
    }
}
subprojects {
    hello {
        doLast {println "- I depend on water"}
        afterEvaluate { Project project ->
            if (project.arctic) {
                doLast { println '- I love to spend time in the arctic waters.' }
            }
        }
    }
}

