docs: static final Map<String, Object> previousAndCurrentToDelta(List<Map<String, Object>> data) {
          if (data.size() == 2) {
              Map<String, Object> previous = data.get(0);
              Map<String, Object> current = data.get(1);
              return previousAndCurrentToDelta(previous, current);
          } else {
              throw new IllegalArgumentException("Must be list of 2 items");
          }
  
      }