[java-okhttp] Restore integration tests #1295

Job	Run time
Gradle tests (samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8)	59s
Gradle tests (samples/openapi3/client/petstore/java/jersey2-java8-special-characters)	1m 3s
Gradle tests (samples/openapi3/client/petstore/java/jersey2-java8)	1m 15s
Gradle tests (samples/client/petstore/java/jersey2-java8-localdatetime)	1m 1s
Gradle tests (samples/client/petstore/java/jersey2-java8)	58s
Gradle tests (samples/client/petstore/java/okhttp-gson)	58s
Gradle tests (samples/client/petstore/java/okhttp-gson-group-parameter)	1m 3s
Gradle tests (samples/client/petstore/java/webclient-swagger2)	1m 42s
	8m 59s

Provide feedback