The "Exceptions" section of MXBean specification says:
--
A problem with mapping from Java types to Open types is signaled with an OpenDataException.
...
A problem with mapping to Java types from Open types is signaled with an InvalidObjectException.
...
Depending on the context, the OpenDataException or InvalidObjectException may be wrapped in another exception such as RuntimeMBeanException or UndeclaredThrowableException.
--

  In other words, these 2 exceptions may be wrapped at ANY other exception. As nothing is said about saving the cause for wrappers - there is no guarantee that a user can determine that a problem occured exact with type mapping.