Override this method to control what should happen when an exception
escapes the
#doPost method. The default implementation will log the
failure and send a generic failure response to the client.
An "expected failure" is an exception thrown by a service method that is
declared in the signature of the service method. These exceptions are
serialized back to the client, and are not passed to this method. This
method is called only for exceptions or errors that are not part of the
service method's signature, or that result from SecurityExceptions,
SerializationExceptions, or other failures within the RPC framework.
Note that if the desired behavior is to both send the GENERIC_FAILURE_MSG
response AND to rethrow the exception, then this method should first send
the GENERIC_FAILURE_MSG response itself (using getThreadLocalResponse), and
then rethrow the exception. Rethrowing the exception will cause it to
escape into the servlet container.