[PUBDEV-2923][JUnit] Separates POJO namespace via using a separated classloader.
[PUBDEV-2923][JUnit] Separates POJO namespace via using a separated classloader.

Each loaded pojo during testing is using a separated classloader to
avoid collision in class names.

michalkurka/h2o-3,h2oai/h2o-dev,michalkurka/h2o-3,h2oai/h2o-3,spennihana/h2o-3,michalkurka/h2o-3,jangorecki/h2o-3,mathemage/h2o-3,h2oai/h2o-dev,mathemage/h2o-3,michalkurka/h2o-3,jangorecki/h2o-3,h2oai/h2o-3,spennihana/h2o-3,michalkurka/h2o-3,mathemage/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,h2oai/h2o-dev,jangorecki/h2o-3,h2oai/h2o-3,h2oai/h2o-3,h2oai/h2o-3,spennihana/h2o-3,spennihana/h2o-3,mathemage/h2o-3,h2oai/h2o-dev,spennihana/h2o-3,h2oai/h2o-dev,mathemage/h2o-3,h2oai/h2o-3,h2oai/h2o-dev,michalkurka/h2o-3,jangorecki/h2o-3,h2oai/h2o-3,jangorecki/h2o-3,mathemage/h2o-3,spennihana/h2o-3,spennihana/h2o-3,mathemage/h2o-3,jangorecki/h2o-3,h2oai/h2o-dev,jangorecki/h2o-3