I’m trying to build Apostrophe using Builder, and am attempting to get it to include the plugin.
Getting the build as default to succeed was straightforward, but I’m getting stuck getting plugin to also build with it. Here is the manifest of the main application [1], and the manifest of the plugin [2].
Issue is, the build configurations panel in Builder only displays the default for the application. Not sure if the plugin manifest is meant to be shown in this panel, or if there is an issue from the current implementation.
In all probability, it is a PEBCAK issue, though I am trying to get it done through Builder, as I’d like it to apply the same sandboxing for the development environment as it does for the main application.
In all honesty, not sure if for plugins are meant to be as easily built, as instructed within the newcomers page for building a project [3], maybe I am a built spoilt with convenience at this point.
I already opened an issue there in more detail, but seems such a basic issue I thought I’d ask here.
Appreciate any help you can provide 
Links mentioned above (sorry, limited to 2 links):
1: https://gitlab.gnome.org/World/apostrophe/-/blob/main/build-aux/flatpak/org.gnome.gitlab.somas.Apostrophe.json
2: https://gitlab.gnome.org/World/apostrophe/-/blob/main/build-aux/flatpak/org.gnome.gitlab.somas.Apostrophe.Plugin.TexLive.json
3: https://wiki.gnome.org/Newcomers/BuildProject