ProjectCompilerVersionChecker.validateProjectComplianceLevel fails in spite of correct Java versions

[PaulCormier]

I have installed "Hibernate Tools - 5.4.23.v20240515-1831" in my instance of Eclipse 2024-12, running on "JustJ JRE for IDE Packages 21.0.0.v20241024-0603", and I'm trying to use a Hibernate configuration in a project with compiler level 1.8 (I also tried 11 and 21). The result is that I get an error message that the project "has a higher compiler option than running Eclipse...".
Looking at the source code for where this message originates, ProjectCompilerVersionChecker, it appears that the JavaCore.COMPILER_CODEGEN_TARGET_PLATFORM is returning a string that is parsed into a higher int value than the parsing of the string returned by System.getProperty("java.specification.version"). I could see decodeJdkVersion returning 0 if the "java.specification.version" property weren't set, but I have no way of verifying what the code sees.

With this check failing, I am unable to use this plugin.