[JaxRsCxfServer] Improvements for generated Unittests and Attachments

[jfiala]

Description

From #4088:

1.) currently in the tests the api invocations are commented out and thus cannot be compiled.
Wouldn't it be good to activate them and run the CI maven build with -DskipTests?

2.) Handling CXF Attachments is not totally intuitive, do you think it makes sense to add an assistance snippet here like this at api_test.mustache (for #isFile):

InputStream mybytesInput = new FileInputStream("....");
org.apache.cxf.jaxrs.ext.multipart.ContentDisposition cd = new org.apache.cxf.jaxrs.ext.multipart.ContentDisposition("attachment;filename=file.txt");
Attachment attachment = new Attachment("file", mybytesInput, cd);

or does that go too far and we should leave with the default Attachment attachment = null;?

Swagger-codegen version

2.2.2-SNAPSHOT

Related issues

#4088 Minor improvements JaxRsCXFServer

Suggest a Fix

[wing328]

1. If I remember correctly, there are certain scenarios (edge cases) in which the test cases won't compile right out of the box so that's why the tests are commented out to start with.

2. I like the idea of the assistance snippet so as to save the developer's time 👍

[jfiala]

For JaxRS-CXF with the contracts we are using for tests everything compiled smoothly, what about activating the tests for Jaxrs-CXF so we proof they actually compile?

[wing328]

@jfiala ok, let's proceed with that.

[jfiala]

added PR to compile the api invocations in unittests for cxf clients.

[jfiala]

Added the snippet to deal with CXF Attachments.

Sidenote: the currently used PetApi.uploadFile with the FormParam additionalMetadata doesn't work with CXF as it only supports one Attachment parameter. If the parameter additionalMetadata is removed, the unittest works.