code: public long getProblemScale(Solution_ solution) {
          long problemScale = 0L;
          for (Iterator<Object> it = extractAllEntitiesIterator(solution); it.hasNext(); ) {
              Object entity = it.next();
              EntityDescriptor<Solution_> entityDescriptor = findEntityDescriptorOrFail(entity.getClass());
              problemScale += entityDescriptor.getProblemScale(solution, entity);
          }
          return problemScale;
      }
docs: Calculates an indication on how big this problem instance is.
  This is intentionally very loosely defined for now.
  @param solution never null
  @return {@code >= 0}