@SuppressWarnings("unchecked")
    static <S> @NonNull SenderMapper<S, S> identity() {
        return (SenderMapper<S, S>) SenderMapperImpl.IDENTITY;
    }
Returns the identity mapper, a mapper that does not transform the sender.

@param <S> base and mapped command sender type
@return identity mapper
cloud-core/src/main/java/org/incendo/cloud/SenderMapper.java