When to set custom headers

If you use a custom CXF interceptor to set one or more outbound HTTP headers then it is recommended to get this interceptor running at a stage preceding the WRITE stage, before the outbound body is written out.

Otherwise the custom headers may get lost. The headers may get retained in some cases even if they are added after the body is written out, example, when a chunking threshold value (4K by default) has not been reached, but relying on it for the headers not to be lost is brittle and should be avoided.