How to use multiple errorformat matchers is not documented anywhere

I have these two errorformat efm patterns I want to use:

%+C %.%#
%W[WARNING] %f:[%l,%c] %m

This works great in the error format playground to match multi-line warnings of the type:

[WARNING] /path/to/Nucleus.java:[213,6] [method.invocation] call to hide() not allowed on the given receiver.
  found   : @UnderInitialization(com.playmonumenta.plugins.depths.bosses.Nucleus.class) @NonNull Nucleus
  required: @Initialized @NonNull Nucleus

However, it took me some trial and error to get reviewdog to actually accept these multiple arguments. This is the right approach, with two -efm arguments:

cat compile.log | reviewdog -efm="%+C %.%#" -efm="%W[WARNING] %f:[%l,%c] %m" -name="demo" -reporter=github-pr-check

Separating with a comma (i.e. the way vi docs describe it) does NOT work:

cat compile.log | reviewdog -efm="%+C %.%#,%W[WARNING] %f:[%l,%c] %m" -name="demo" -reporter=github-pr-check

Ideally I'd like the documentation to be updated to explain this. If not though, feel free to close this issue - at least someone in the future who is looking for this will likely find this issue and discover the answer