include HTTP request Content-Length header value in request.log

Sometimes problem diagnosis in Nexus Repository Manager may benefit from knowing the inbound http request anticipated content size.

For a large majority of requests to add content into Nexus, HTTP PUT is used. In those cases, the request content size information is usually available from the HTTP request Content-Length header value.. ( there are some exceptions, in particular "When a message does not have a Transfer-Encoding header field, a Content-Length header field can provide the anticipated size, as a decimal number of octets, for a potential payload body." )

Expected

The default request.log log pattern for Nexus should be adjusted to include the value if any of the Content-Length header of the request.

Current pattern as of nexus 3.10.0

%clientHost %l %user [%date] "%requestURL" %statusCode %bytesSent %elapsedTime "%header{User-Agent}"

Proposed new format:

%clientHost %l %user [%date] "%requestURL" %statusCode %header{Content-Length} %bytesSent %elapsedTime "%header{User-Agent}"

This change should be announced in release notes in case users have configured external request log parsers which may need adjustment or prefer to not have this value printed.