Method of

guava/src/com/google/common/collect/ImmutableMap.java:123–126

Returns the empty map. This map behaves and performs comparably to Collections#emptyMap, and is preferable mainly for consistency and maintainability of your code. Performance note: the instance returned is a singleton.

()

   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableMap<K, V> of() {
    return (ImmutableMap<K, V>) RegularImmutableMap.EMPTY;
  }

  /**
   * Returns an immutable map containing a single entry. This map behaves and performs comparably to