getting messages "No content-type found with id='lng.properties', ignoring TM4E association."

[jcompagner]

when we use the tm4e in our product we get this:

!ENTRY org.eclipse.tm4e.registry 2 0 2022-12-14 14:14:51.224
!MESSAGE No content-type found with id='lng.properties', ignoring TM4E association.

!ENTRY org.eclipse.tm4e.registry 2 0 2022-12-14 14:14:51.225
!MESSAGE No content-type found with id='lng.markdown-math', ignoring TM4E association.

if i look at this file:
https://github.com/eclipse/tm4e/blob/master/org.eclipse.tm4e.language_pack/plugin.xml

then many (like lng.markdown itself) has a grammar and a content type specified
but those are missing for the other 2, is that on purpose?