Currently the audit log only logs webhdfs vs rpc as the proto. It is useful to be able to audit whether certain commands were carried out via webhdfs or swebhdfs as this has different security and potentially performance implications. We have been running this internally for a while and have found it useful for looking at usage patterns.
Proposal is just to continue logging webhdfs as the proto for http WebHDFS commands, but log swebhdfs for SWebHDFS (over https). This will be incompatible.