End the current request. It is acceptable to write extra bytes using
buffer.doWrite during the execution of this method.
return
Should return 0 unless the filter does some content length
delimitation, in which case the number is the amount of extra bytes or
missing bytes, which would indicate an error.
Note: It is recommended that extra bytes be swallowed by the filter.
Some filters need additional parameters from the response. All the
necessary reading can occur in that method, as this method is called
after the response header processing is complete.