Added Swagger-Core to generate the OpenAPI file on the fly

[gerardnico]

Motivation:

I have added Swagger-Core in the example.
The rest easy 4.0.0 example was not working already. I got an issue over unknown function.
I have downgraded it to 3.8. I know this is a 4.0 branch.

Conformance:

No problem to conform and to sign whatever is needed.

Your commits should be signed and you should have signed the Eclipse Contributor Agreement as explained in https://github.com/eclipse/vert.x/blob/master/CONTRIBUTING.md
Please also make sure you adhere to the code style guidelines: https://github.com/vert-x3/wiki/wiki/Vert.x-code-style-guidelines

[vietj]

@gerardnico how can we solve this version mismatch ?

[gerardnico]

I can put it back to 4.0.0 but it will not work.
This is just to alert on the fact that this example was not working in 4.0.0.

I can put it back to 4.0.0 but I does not have the vertx core knowledge to resolve it.
I got a function not known if I remember well.

[gerardnico]

I just saw that you were already at 3.9.5. I made the update and added a test.

The error that I get with 4.0.0 is:

SEVERE: Unhandled exception
java.lang.NoSuchMethodError: io.vertx.core.http.HttpServerRequest.rawMethod()Ljava/lang/String;
	at org.jboss.resteasy.plugins.server.vertx.VertxRequestHandler.lambda$handle$0(VertxRequestHandler.java:56)
	at io.vertx.core.impl.future.FutureImpl$1.onSuccess(FutureImpl.java:91)
	at io.vertx.core.impl.future.FutureBase.lambda$emitSuccess$0(FutureBase.java:53)
	at io.vertx.core.impl.EventLoopContext.execute(EventLoopContext.java:83)

[gerardnico]

This commit 99194a9 resolve a bug. The template engine expects the vertx object but because it was static, it got a null object
The other just get rid of the static cache which is annoying when you are going through the examples.

[vietj]

what does not work with 4.0.0 ? can you elaborate what is blocking you ?

[gerardnico]

I already did yesterday and I understand that it's confusing.

The stack trace is

SEVERE: Unhandled exception
java.lang.NoSuchMethodError: io.vertx.core.http.HttpServerRequest.rawMethod()Ljava/lang/String;
	at org.jboss.resteasy.plugins.server.vertx.VertxRequestHandler.lambda$handle$0(VertxRequestHandler.java:56)
	at io.vertx.core.impl.future.FutureImpl$1.onSuccess(FutureImpl.java:91)
	at io.vertx.core.impl.future.FutureBase.lambda$emitSuccess$0(FutureBase.java:53)
	at io.vertx.core.impl.EventLoopContext.execute(EventLoopContext.java:83)

This is an error with the RestEasy Plugin that expects HttpServerRequest.html#rawMethod and can't found it anymore in 4.x