feature: better collection-based properties of Spoon model (non-derived getters)

[pvojtechovsky]

Example of problem: Use case: Client needs to add argument at the beginning of CtInvocation#arguments list.
Actually the only solution is

List<CtExpression<?>> args = new ArrayList<>(invocation.getArguments());
args.add(0, newArgument);
invocation.setArguments(args);

Solutions?

S1) to have method CtInvocation#addArgument(int, CtExpression)
S2) to have method CtInvocation#addFirstArgument(int, CtExpression)

it is the way how Spoon handles it actually. Each element implements (or does not implement (... yet?)) own set of collection manipulation methods. May be we might generate all possible add/addList/remove/contains methods of Set and List interface with appropriate attribute name suffix automatically.
It would be compatible with current model, but

• it would mean a lot of methods in spoon API - more complicated for clients
• it avoids usage of generic helper methods, which are able to do operations on List and Set

S3) to have method List CtInvocation#getArguments(), which would return modifiable implementation of List.

We cannot of course return internal list and let client to modify it.
The idea is to return a List/Set wrapper which would handle all the List/Set method calls. It would

• generate appropriate model change events
• handle consistency of model (change parent, ...)

It would be not backward compatible, but the code of spoon and code of client's would be simpler and spoon API would be more friendly to clients who needs model modifications.

S4) to use generic List modifiableList = invocation.getValueByRoleAsList(CtRole.ARGUMENT)

This is already partially implemented in #1582.

• I like that API, because it will be useful for some special kind of model operations.
• But it is not so nice solution like S3 would be, because client has to access attributes by CtRole.ARGUMENT, which is more complicated then simple call of List getArguments()
• Current implementation of review: feat: Spoon CtRole based attributes access #1582 is based on current spoon model (get/setArguments(...), ...). If S3 would be already implemented in spoon model, then implementation of review: feat: Spoon CtRole based attributes access #1582 would be much simpler too.

[monperrus]

closed per #1582