code: public static <K, V> TreeMap<K, V> treeMapOf(K k1, V v1, K k2, V v2) {
      TreeMap<K, V> treeMap = new TreeMap<>();
      treeMap.put(k1, v1);
      treeMap.put(k2, v2);
      return treeMap;
    }
docs: Returns a {@link TreeMap} of the given entries, in order.