A DESCRIPTION OF THE PROBLEM :
JDK-8039273 considers the "lib/font/fallbacks" a mis-feature and removed it while performing the move from ${java_home}/lib to ${java_home}/conf.
The problem is that applications that the feature helped did not disappear and their users are now struggling with font-portability issues when they move to new platforms. Yes, the applications may be badly written and probably deserve some slapping or even some editing after decompilation for its use of explicitly-named fonts, but breaking a not-so-bad (even *great* as GNU freefont/unifont is a thing) solution to this problem is Orcale's fault.
Please, just bring {lib,conf}/font/fallbacks, or to say in the terms of your internals, getInstalledFallbackFonts, back.