Missing details on 'expression-filter'

While working on a critical issue for one of my TAM customers, it was identified that our EAP-7 docs do not cover much of the available "expression-filter" parameters.
In my specific use case, the customer had to use this filter which resolves/meets their business as below.

~~~
<expression-filter name="buf" expression="buffer-request(buffers=1)"/>
<filter-ref name="buf"/>
~~~

We got acquainted with this only when we reached out to the Engineering team for help on the issue.

The interesting part is that nothing is available in community docs too.

Now, the customer is worried about the above filter's supportability since there wasn't anything in our docs.

We need have this particular part added to the docs, be it in an example format or similar.

Please let me know what process you follow to get this added. I will then be providing more details on what that filter does so that it becomes easy for you guys to summarize and add.

[1] https://access.redhat.com/documentation/en-us/red_hat_jboss_enterprise_application_platform/7.1/html/configuration_guide/configuring_the_web_server_undertow#undertow-configure-filters