/kind feature

Describe the solution you'd like
Sometimes when logging request/responses using the logger system it might be needed to log extra data. This might be metadata related to the request (location, language, etc)

Would be nice to be able to specify some prefix in the config so that when users send a request with headers containing that prefix the values get sent to the logger in the metadata field

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Links to the design documents:
[Optional, start with the short-form RFC template to outline your ideas and get early feedback.]
[Required, use the longer-form design doc template to specify and discuss your design in more detail]