Custom marshal callback interface mimicking JAXB class based marshal
Some JAXB implementations (e.g. EclipseLink MOXy 2.2) are broken and class
defined marshal/unmarshal callbacks are not invoked. This is a workaround to
avoid problems in some application server which switched from Sun RI to MOXy.
To avoid name clashes beforeMarshal equivalent is called preMarshal and
afterMarshal is called postMarshal