The following in build.gradle should be changed to use jfxReleaseMajorVersion property rather than a hard-coded number 8:

1708: commandLine("$RC", "/nologo", "/l", "0x409", "/r", "/dJFX_DVERSION=8", "/dJFX_VERSION=8",
1709: "/fo$buildDir/native/javafxpackager/javafxpackager.res",
1710: "src/main/native/javafxpackager/win/javafxpackager.rc");