private Set<ShapeId> findRemoved(Set<ShapeId> oldShapes, Set<ShapeId> newShapes) {
        Set<ShapeId> removed = new HashSet<>(oldShapes);
        removed.removeAll(newShapes);
        return removed;
    }
A meta-validator that checks for the removal of an operation or
resource binding from a service or resource.

<p>A "RemovedOperationBinding" eventId is used when an operation is
removed, and a "RemovedResourceBinding" eventId is used when a
resource is removed.
smithy-diff/src/main/java/software/amazon/smithy/diff/evaluators/RemovedEntityBinding.java