One of the changes introduced in 11.x (11.0, specifically) was the removal of the macros.ftl reference in notification templates. These templates enable customized notifications (primarily syslog and email) using freemarker syntax. The 10.x templates relied on macros (which are basically just functions, but using freemarker terminology) to build out and populate both the OOTB and (most likely) custom notifications.
If you upgraded from 10.x to 11.x and you had any custom notifications, there's a very good chance you noticed that these notifications failed, and if you dug into logs you'd have probably found an error like this:
The good news is there's a very easy fix for this, and it does not require re-writing any of your 10.x notifications. The contents of macros.ftl file that was previously used in 10.x simply need to be copy/pasted into your existing notification templates, replacing the <#include "macros.ftl"/> line, and they'll continue to work the same as they did in your 10.x environment (props to Eduardo Carbonell for the actual testing and verification of this solution).
I have attached a copy of the macros.ftl file to this blog, or if you prefer you can find the same on any 11.x ESA host in the "/var/netwitness/esa/freemarker" directory.