Functions such as HttpClientRequest.getAbs have changed signature in Vert.x 4 (it is impossible to support both 3.X and 4 a the same time).

https://vertx.io/docs/apidocs/io/vertx/core/http/HttpClient.html#get-int-java.lang.String-java.lang.String-io.vertx.core.Handler-

Deprecated. this method signature will change in Vert.x 4, the handler will use an Handler<AsyncResult<HttpClientResponse>>, you can use instead the WebClient
Create an HTTP GET request to send to the server at the specified host and default port, specifying a response handler to receive the response