docs: private static void putToMapIfNotThere(Map<String, Integer> symbolsMap,
                                             String text, int sid)
      {
          // When there's a duplicate mapping for the symbol text, don't
          // replace the lower sid. This pattern avoids double-lookup in the
          // common scenario and only performs a second lookup when there's
          // a duplicate.
          Integer extantSid = symbolsMap.put(text, sid);
          if (extantSid != null)
          {
              // We always insert symbols with increasing sids
              assert extantSid < sid;
              symbolsMap.put(text, extantSid);
          }
      }