Orcan Ogetbil wrote:
Let's make this clear: .jar files are nothing but containers of
.class files and a manifest file, right?
A JAR file can have a bit more functions
than providing a simplest ZIP
archive of .class files and a manifest file.
But, globally you are right, JAR is container for resources intended to
be used by Java program(s).
Complete info about it in the JAR File Specification  .
IMHO Ideally, a JAR file in the target software package (i.e. in the
binary RPM) should be the same as the JAR file that is originally
provided by its Java software project.
Of course, it is true only if there are no intentions to change original
behavior of the Java applications that are based on that JAR file.
BTW Such viewpoint gives me idea that repackaging of JARs via
brp-java-repack-jars is not good for pure Java software at all.
Note, it doesn't meet a requirement declared in the message  :
"... a jar ... needs to be repacked if (a) it is destined for