open fun close(): Unit
Stop the the Vertx instance and release any resources held by it.
The instance cannot be used after it has been closed.
The actual close is asynchronous and may not complete until after the call has returned.
open fun close(completionHandler: Handler<AsyncResult<Void>>): Unit
Like io.vertx.reactivex.core.Vertx#close but the completionHandler will be called when the close is complete
completionHandler - The handler will be notified when the close is complete.