code: static Map<Integer, Integer> levelsToIndices(Map<String,String> meta) {
          Set<Map.Entry<String, String>> entries = meta.entrySet();
          Map<Integer, Integer> levelToIdx = new HashMap<>();
          for(Map.Entry<String,String> entry : entries)
              if(entry.getKey().endsWith(ARRAY_IDX_SUFFIX))
                  levelToIdx.put(parseInt(entry.getKey().substring(0, entry.getKey().indexOf('.'))), parseInt(entry.getValue()));
  
          return levelToIdx;
      }
docs: Converts all array index information in a given map of metadata to a map that is keyed only
  by the level and each value is the index in the array for that level. This is used to
  optimize lookup since a string is used for the key in the metadata that should not conflict
  with keys that other applications may want to set.
  @param meta
  @return