Fixes order problem in client user code deployment

[sancar]

The issue is related to inheritance. If a a ChildClass is configured
first, it was trying to be defined first. It was searching for its
parent, and failing.
The issue is fixed by loading the parent class definition when needed,
from bundledClassDefinitions on the server.
(these are the whole classes send together from the client)

fixes #16575

(cherry picked from commit c9b0bcc)

[galibey]

@sancar But definition size doesn't correlate with inheritance. It depends only on amount of bytecode in the class. In your unit-tests, if we change ParentClass to something like this:

public class ParentClass implements Serializable, Runnable {

    @Override
    public void run() {

    }
}

tests will fail.

[sancar]

Yes, you are right. I assumed that child will always have the bytecode of its parent, and some more on top of it. Let me think another way to solve this.

[puzpuzpuz]

I think, the correct order of classes (hierarchy) can be determined via Reflection API.

[sancar]

@ihsandemir @galibey @galibey I have updated the pr for the inheritance order problem.

[ihsandemir]

would this also do the same?

        Collections.sort(classes, (c1, c2) -> c1.equals(c2) ? 0 : c1.isAssignableFrom(c2) ? -1 : 1);

[sancar]

It is not a correct comparator implementation, because it does not give a total order. See this question and answer
https://stackoverflow.com/questions/50921813/how-to-sort-classes-according-to-their-inheritance-level#comment88888102_50922334

[galibey]

The fix doesn't cover classes loaded from jars. The issue is relevant for them as well.

[sancar]

@galibey I have checked the jars. Indeed, they are also causing the same problem. I changed my solution after realizing that. Can you review my solution in the last commit ?

[galibey]

@sancar Good solution 👍