review: fix: Unsettable properties sets no value or sets different primary value

[pvojtechovsky]

Here is the test, which reports inconsistencies in Spoon model role get/set.

Generally there are these issues:
P1) Unsettable property CtXxxReference#comment<java.util.List<spoon.reflect.code.CtComment>> sets the value
P2) UnsettableProperty CtEnumValue|CtLocalVariable|CtField#assignment<spoon.reflect.code.CtExpression> sets the value into different role defaultExpression
P3) UnsettableProperty CtLambda#thrown<java.util.Set<spoon.reflect.reference.CtTypeReference<? extends java.lang.Throwable>>> sets the value
P4) Settable field CtCatchVariable#type<spoon.reflect.reference.CtTypeReference> is accessible by multiType too

I am not sure whether we should solve these problems. May be they are features for somebody?

Solutions might be

P1

to implement empty CtReference#setComment().

P2

??

P3

to implement empty CtLambda#setThrownTypes

P4

to mark role CtCatchVariable#TYPE as derived

WDYT?

[monperrus]

OK for me. For P2, I would simply remove the @DerivedProperty (the API documentation is clear about the goal).

[pvojtechovsky]

The @DerivedProperty on getter is no problem. The problem is meaning of @UnsettableProperty. I understand the meaning: "you can call this method, but it will do nothing" ... but this contract is broken by code like

class CtFieldImpl { ...
	@UnsettableProperty
	public <C extends CtRHSReceiver<T>> C setAssignment(CtExpression<T> assignment) {
		setDefaultExpression(assignment);
		return (C) this;
	}

May be we can live with that, I just wanted to be sure that we speak about the same thing.

[monperrus]

My bad, I indeed meant UnsettableProperty:

For P2, I would simply remove the @UnsettableProperty (the API documentation is clear about the goal).

[pvojtechovsky]

I am mainly not sure with CtLambdaImpl#setThrownTypes, where I deleted code added by You ;-)
A) it is correct, it has to be deleted
B) we have to remove UnsettableProperty from CtLambda#setThrownTypes

So if you agree with A), then this is finished

[monperrus]

OK for me. Will merge it.