Gradle property in a GString

build.gradle

class PingServer extends DefaultTask {
    @Input
    final Property<CharSequence> fqdm = project.objects.property(CharSequence)

    @TaskAction
    void ping() {
        println "Pinging ${fqdm.get()}"
    }
}

class Server implements Named {
    final String name

    final Property<CharSequence> hostName

    Server(String name, Project p) {
        this.name = name
        hostName = p.objects.property(CharSequence)
    }

    void setHostName(CharSequence g) {
    	 hostName.set(g)
    }
}

class MyExt {
    Property<CharSequence> domainName

    private NamedDomainObjectContainer<Server> servers

    MyExt(Project p) {
        domainName = p.objects.property(CharSequence)
        domainName.set('')

        servers = p.container(Server) { final name -> new Server(name, p) }
        servers.all { final server ->
            server.hostName.set("${server.name}${-> domainName.get()}")

            final createServer = p.tasks.create("ping${server.name.capitalize()}", PingServer)
            createServer.fqdm.set(server.hostName)
        }
    }
    
    void servers(Closure c) { servers.configure(c) }
}

project.extensions.create("myExt", MyExt, project)

myExt {
    servers {
        fe1 {}
        be1 {
            hostName = "backend1${-> domainName.get()}"
        }
    }
    domainName = ".example.com"
}