review fix: fix bug with repeatable annotations

[surli]

fix #1722

[surli]

This PR intends to fix #1722 but it also fixes cases when trying to annotate twice on an annotation type that does not take an Array: the current behavior was to create an array nevertheless, now it throws a SpoonException.

I also had to make a choice when calling repeatedly annotate with a String value on this kind of annotation:

@Repeatable(Tags.class)
public @interface Tag {
    String[] value();
}

We could have indeed those different results:

@Tag("value1")
@Tag("value2")
@Tag("value3")
void foo1();

@Tag({"value1", "value2"})
@Tag("value3")
void foo2();

@Tag({"value1", "value2", "value3"})
void foo3();

Previous behaviour did not take into account the @Repeatable meta-annotation of annotation, so the results corresponding to foo3 were used (then issue #1722), but now with the fix proposed I consider that we should check in priority if the annotation is repeatable or not: if it is, then it creates a new annotation in priority. In this example, foo1 would be created with this new behaviour. foo2 is reachable only if the user decides first to call annotate with an array and then with a single string value.

My guess is that if the user really wants to put an array of objects in the value, then it can always annotate with the array of objects, instead of calling multiple times annotate.

[pvojtechovsky]

I have checked this PR and it looks good for me. I would merge it but the meaning of word "factorized" in the title is not clear for me. So I am just not sure with merge comment ...

[monperrus]

fixed title. ready for merge!