[JAVA][library: vertx] Generated async and rx sample server code fails 'mvn test'

[ccozzolino]

Description

Originally reported by @wing328 in #7230

mvn test fails for the server samples generated by
java-vertx-async-petstore-server.sh
java-vertx-rx-petstore-server.sh

Original template attempts to instantiate a non-generated class leading to a compile error.

To fix, we can use reflection to push instantiation of the required class to runtime.

Swagger-codegen version

All versions that with vertx async & rx support

Swagger declaration file content or url

Command line used for generation

Steps to reproduce

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