[3.0.0] Update 'java' examples (2)

[jmini]

See: swagger-api/swagger-codegen-generators#52

This is the second part, after the first part made with #7932.

Fixes made in swagger-api/swagger-codegen-generators#53 needs to be merged first.

[jmini]

Now that swagger-api/swagger-codegen-generators#53 is merged, I have updated this pull request.

Script executed to update the examples:

#!/bin/sh
# update # java petstore for all supported http libraries

./bin/java-petstore-jersey2-java6.sh

./bin/java-petstore-okhttp-gson.sh
./bin/java-petstore-okhttp-gson-parcelable.sh

./bin/java-petstore-feign.sh
./bin/java-petstore-jersey1.sh
./bin/java-petstore-jersey2.sh
./bin/java-petstore-resteasy.sh
./bin/java-petstore-resttemplate-withxml.sh
./bin/java-petstore-resttemplate.sh
./bin/java-petstore-retrofit.sh
./bin/java-petstore-retrofit2-play24.sh
./bin/java-petstore-retrofit2-play25.sh
./bin/java-petstore-retrofit2.sh
./bin/java-petstore-retrofit2rx.sh
./bin/java-petstore-retrofit2rx2.sh
./bin/java-petstore-vertx.sh
./bin/java8-petstore-jersey2.sh

[jmini]

@HugoMario: I think this can be merged.

[HugoMario]

thanks @jmini !!