exampleThenable.js

// a Java object implementing the `then` method (created from Java)
let javaExecutor = Java.type('some.awesome.Klass').createNew();
// create a JavaScript promise
let interopPromise = new Promise(javaExecutor);
// register some promise reactions
interopPromise.then(result => { console.log('Java resolves: ' + result); },
                    error => { console.log('Java rejects: ' + error); });