The Felix class currently normalizes the processor name and os name system property before putting it into the framework properties.
Likewise the os version system property should be normalized as well.
Symptom of not normalizing the os version is the ExtensionManager.buildNativeCapabilites method failing to create the os version.
Alternatively, the ExtensionManager.buildNativeCapabilites method could itself normalize the os.version framework property. This would prevent the method from failing and would still allow the R4LibraryClause to match an os version capability (R4LlibraryClause does normalize the os version in the clause of the bundle before matching).