This patch adds note option to squid.conf. It is similar to
adaptation_meta but is applied after all adaptation and before logging.
Values of key/value pair notes can be logged using %{key}note macros.
note key value acl ...
logformat myFormat ... %{key}note ...
This option may be initially used to log custom information about the master
transaction. For example, an admin may configure Squid to log which "user group"
the transaction belongs to, where "user group" will be determined based on a
set of ACLs and not [just] authentication information.
From user point of view, adaptation_header sets/implies meta (i.e.,
setting adaptation_meta is sufficient to be able to log it using
%note) but the note option itself (if any) is evaluated later,
so it has no effect on ICAP headers.