LoggerContextVO offers a restricted view of LoggerContext intended to be
exposed by LoggingEvent to remote systems. This restricted view is optimized
for serialization.
Some of the LoggerContext or Logger attributes MUST not survive
serialization, e.g appenders, level values etc, as these attributes may have
other values on the remote platform. LoggerContextVO class exposes the
minimal and relevant attributes to the remote host, instead of having to deal
with an incomplete LoggerContext with many null references.