New to the team and project, but this seems to be very much the case. I will say that the core of FreePBX is made up of many modules, each can be found in their own git repository. All of these modules are protected with signatures, so any updates needs to be signed to protect the module from being tampered with. It does take a bit of time to wrap your head around.
There are few other tools you can use defined here including dev tools:
https://wiki.freepbx.org/display/FOP/Setting+up+a+Development+environment+from+the+FreePBX+Distro
Module Signing:
https://wiki.freepbx.org/pages/viewpage.action?pageId=29753662