docs: private void getCommandsToDiff(String mapName,
                                     CatalogMap<? extends CatalogType> prevMap,
                                     CatalogMap<? extends CatalogType> newMap)
      {
          assert(prevMap != null);
          assert(newMap != null);
  
          // in previous, not in new
          for (CatalogType prevType : prevMap) {
              String name = prevType.getTypeName();
              CatalogType newType = newMap.get(name);
              if (newType == null) {
                  writeDeletion(prevType, newMap.m_parent, mapName);
                  continue;
              }
  
              diffRecursively(prevType, newType);
          }
  
          // in new, not in previous
          for (CatalogType newType : newMap) {
              CatalogType prevType = prevMap.get(newType.getTypeName());
              if (prevType != null) continue;
              writeAddition(newType);
          }
      }