SameLen on custom collections requires a suppressed warning to establish representation invariant

[kelloggm]

Typically this needs to happen in the constructor. For example, consider the following class:

class MyArray<T> {
    T @SameLen("this") [] backingArray;

    @SuppressWarnings("index") // establish representation invariant
    public MyArray(@NonNegative int length) {
         backingArray = new T[length];
    }
 
    public @LengthOf("this") int length() { return backingArray.length; }
    public T get(@IndexFor("this") int index) { return backingArray[index]; }
}

Ideally, this suppressed warning wouldn't be required. It's not really a false positive, so we should replace it with an annotation.

[mernst]

Is an annotation needed, and if so which one? It would be nicer if the checker could had logic to permit an assignment to a @SameLen("this") field in the constructor (perhaps with some caveats).