[RESTEASY-3300] Do not append single '&' with empty query parameters

[Dkafetzis]

Fixed this Jira Issue (https://issues.redhat.com/browse/RESTEASY-3300) and added an integration test for this case

[wildfly-ci]

Hello, Dkafetzis. I'm waiting for one of the admins to verify this patch with /ok-to-test in a comment.

[jamezp]

/ok-to-test

[jamezp]

We could actually test this with standard API's rather than internal ones. We could use a ContainerRequestFilter and get the URI from there to check. In some ways this would be the preferred way IMO.

If we want to stick with using internal API's we should have a method like:

private static Client createClient(final String expectedQuery) {
    ResteasyClientBuilder builder = (ResteasyClientBuilder) ClientBuilder.newBuilder();
    ResteasyClient client = builder.httpEngine(new ClientHttpEngine() {
        @Override
        public Response invoke(Invocation request) {
            Assert.assertEquals(expectedQuery, ((ClientInvocation) request).getUri().getQuery());
            return new AbortedResponse(null, new ServerResponse());
        }

        @Override
        public SSLContext getSslContext() {
            return null;
        }

        @Override
        public HostnameVerifier getHostnameVerifier() {
            return null;
        }

        @Override
        public void close() {
        }
    }).build();
}

This would avoid us repeating similar patterns in the test.

This is a little OT for this PR, but I want to remove the usages of ResteascyClientBuilder and the ResteasyClient in the test suite where we can. We should be using standard API's for this as they are available.

[Dkafetzis]

@jamezp Changes implemented, waiting for review.

[jamezp]

/retest

[jamezp]

These Windows test failures are from the test added. Do you have access to a Windows VM @Dkafetzis? If not I have a look locally.

[Dkafetzis]

@jamezp should be fine now. Give it another test run

[Dkafetzis]

@jamezp All tests passed, I think we can merge this.

[jamezp]

replaced by #3570