builder.put(k4, v4);
    builder.put(k5, v5);
    return builder.build();
  }

  // looking for of() with > 5 entries? Use the builder instead.

  /**
   * Returns a new builder. The generated builder is equivalent to the builder created by the {@link
   * Builder} constructor.
   */
  public static <K, V> Builder<K, V> builder() {
    return new Builder<>();
  }

  /**