@catshome Thank you for pointing me to the new builds. I first tried the one in the Matrix folder, but that one has had the libbluray changes removed I think.
Then I noticed there is a separate blu-ray test version in the Test folder, so I tried that one. I noticed it's only a 32-bit version, so I installed the 32-bit version of the Java addon too.
But unfortunately, blu-ray menus still won't work with this version. When selecting "Show blu-ray menu" in Settings -> Player -> Disc, the error "There was an error encountered loading Java" is displayed.
I checked the special://xbmcbin directory and the Java addon is present there.
Maybe the Shield requires 64-bit Java and won't work with 32-bit, but I am not sure about that.
Would be cool if @Maven could build a 64-bit test version too.