* [feign] add threetenbp support for feign clients
* [okhttp] add threetenbp support for okhttp clients
* [jersey] add threetenbp support for jersey clients
* [retrofit2] add threetenbp support for retrofit2 clients
* [spring] add threetenbp support for spring generators
* add a workaround in tests for a bug in the petstore
The petstore doesn't manage fractional digits of dates correctly when there are less than 3
by fixing the logic of enum Boolean checking.
Other changes:
* Remove the `true &&` prefix from the `equals` method in models.
* Apply some changes of Java-default to Java-okhttp-gson, i.e. adding
`this` and parent model handling.
* Some improvements on spaces and blank lines.
