For example, suppose package physics contains a Math class that’s identical to java.lang ‘s Math class in that it implements the same PI constant and trigonometric methods.

I intentionally included three attributes in the MANIFEST.MF example above that are not accessible from Java’s Package class. These are Package-Title, Package-Version, and Package-Vendor.

While there are workarounds -- for example, you could introduce a Factory class to generate transaction objects -- this adds complexity and could become a maintenance burden. Another approach could be ...