code: static private H2ONode intern(H2Okey key, short timestamp) {
      final boolean foundPossibleClient = H2O.decodeIsClient(timestamp);
      H2ONode h2o = INTERN.get(key);
      if (h2o != null) {
        if (foundPossibleClient || h2o.isPossibleClient()) {
          h2o.refreshClient(timestamp);
        }
        return h2o;
      } else {
        if (foundPossibleClient) {
          // We don't know if this client belongs to this cloud yet, at this point it is just a candidate
          Log.info("New (possible) client found, timestamp=" + timestamp);
        }
      }
      final int idx = UNIQUE.getAndIncrement();
      assert idx < Short.MAX_VALUE;
      h2o = new H2ONode(key, (short) idx, timestamp);
      H2ONode old = INTERN.putIfAbsent(key, h2o);
      if (old != null) {
        if (foundPossibleClient && old.isPossibleClient()) {
          old.refreshClient(timestamp);
        }
        return old;
      }
      synchronized (H2O.class) {
        while (idx >= IDX.length) {
          IDX = Arrays.copyOf(IDX, IDX.length << 1);
        }
        IDX[idx] = h2o;
      }
      return h2o;
    }
docs: *interned*: there is only one per InetAddress.