JRuby FTBFS from missing Maven plugin

Hello,

I've been trying to figure out bug #1091127 [0] but I'm stumped:

[ERROR] Plugin org.apache.maven.plugins:maven-assembly-plugin:3.7.1 or 
one of its dependencies could not be resolved

There was no change to the source, so I believe this error might have 
been triggered by the Maven updates that were made lately in Debian.

In the JRuby source package, I had simply been patching out the plugin 
version [1] and it was working out fine, but now something is requesting 
version "3.7.1" of this plugin and I have no idea where or why or what.

If I instead patch in the real version of maven-assembly-plugin that's 
available in Debian, "3.4.2", then the build works.

I'd appreciate some guidance as to what's the correct way to fix this.

Thanks!

-- Jérôme


[0] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1091127
[1] 
https://sources.debian.org/src/jruby/9.4.8.0%2Bds-1/debian/patches/0001-patch-ruby-poms.patch/#L143-L144