This policy rewrites events by evaluating any
JavaBean properties on the message object and adding them
to the event properties. If the message object has a
message property, the value of that property will be
used as the message for the rewritten event and will
not be added to the event properties. Values from the
JavaBean properties will replace any existing property
with the same name.
The combination of the RewriteAppender and this policy
performs the same actions as the ReflectionFilter from log4j 1.3.