Thanks for including the draft of the SRU text.  I've got a few suggestions but they won't affect the review of the packaging so will give them separate.

[Impact]

What the SRU team looks for here is more of an explanation of why the bug deserves to be accepted as SRU.  So, explaining how it impacts end users - i.e. how it disrupts their usage of the software - is important.  Sometimes that requires explaining acronyms or other jargon that may not be generally known by Ubuntu developers; Wikipedia often comes to the rescue here *grin*.

However, at the same time I'd avoid using judgement words like "impossible", "unusable", "randomly", etc. that bug reporters frequently tend to use.  They might mean one thing to one person, and something different to another.  Usually these can be restated in a more precise way without too much difficulty.

One non-obvious thing about the impact section, is that the SRU team doesn't really care about how the bug occurs or how it is fixed, that's almost like an implementational detail.  They suggest moving that to a [Discussion] section, particularly if the explanation is wordy, but if possible I usually try to include a brief statement about how the issue is fixed.

So, with all that, I'd suggest editing the impact section a bit:

[Impact]
The Apache JServe Protocol (AJP) proxies inbound requests to an application server, such as health checks via CPING/CPONG.  mod_proxy_hcheck added support for AJP/CPING in 22.04, however the following error is encountered when enabling it, which prevents the new feature from operating:

   BalancerMember Health check method CPING not (yet) implemented

This is caused by a incorrect check for AJP support in hc_post_config() that occurs too late, after the configuration syntax has already been marked invalid by the time the "hcmethod=CPING" token is found.  The fix is to move the check from hc_post_config() to hc_pre_config(). 


[Where problems could occur]

What you've written is all true, but much of that is generically true of any SRU.  So, I don't think it hurts to include it, but I think what the SRU team is looking for is more about what is distinctive of *this* SRU.

Often I like to think of this section as answering the question, if I were an Apache2 user and updated to this version of the package, and something weird started happening, what types of bugs would I reasonably suspect are this update's fault, vs. ones that are likely to be unrelated?  Usually to answer that you consider what the patch actually does, and if there was an undiscovered error in the code what kinds of failures would we expect to see?

So in this case, the patch itself modifies the code of mod_proxy_hcheck, so any new bugs involving that module would be suspect.  The patch changes configuration code, so issues cropping up that seem related to module configuration could be suspect.  Finally, since the patch modifies C code, issues typical of C code (segfaults, memory leaks, etc.) would be plausible, however since this moves a chunk of code unmodified this seems extremely unlikely.

[Test Plan]
The test case looks great.  I'll run through it while doing the packaging review, but on read through it looks perfect.