I am writing a method that needs to break a delta into pieces (e.g. two deltas that result in the same patch as the original delta). The current design is problematic because:

1. I don't want my method to know/care what the delta type is.
2. The AbstractDelta class is abstract, so I cannot simply invoke its constructor.
3. The AbstractDelta subtypes do not provide with() methods.
4. Some of your code (e.g. DiffRowGenerator) check the class type instance (e.g. if (delta instanceof InsertDelta) instead of using AbstractDelta.getType() so I cannot subclass AbstractDelta myself.

Probably the easiest way to resolve this is to add an abstract withChunks(Chunk<T> original, Chunk<T> revised) method to AbstractDelta.