code: public static final H2ONode intern( H2Okey key ) {
      H2ONode h2o = INTERN.get(key);
      if( h2o != null ) return h2o;
      final int idx = UNIQUE.getAndIncrement();
      h2o = new H2ONode(key,idx);
      H2ONode old = INTERN.putIfAbsent(key,h2o);
      if( old != null ) 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.