private static final int BYTE_MASK = (1 << Byte.SIZE) - 1; // 2^8 - 1 = 255
  private static final int SHORT_MASK = (1 << Short.SIZE) - 1; // 2^16 - 1 = 65_535

  @SuppressWarnings("unchecked")
  static final ImmutableMap<Object, Object> EMPTY =
      new RegularImmutableMap<>(null, new Object[0], 0);

  /*

  /*
   * Arrays are a mess from a nullness perspective, and Class instances for object-array types are
   * even worse. For now, we just suppress and move on with our lives.
   *
   * - https://github.com/jspecify/jspecify/issues/65
   *
   * - https://github.com/jspecify/jdk/commit/71d826792b8c7ef95d492c50a274deab938f2552
   */
  /*
   * TODO(cpovirk): Is the unchecked cast avoidable? Would System.arraycopy be similarly fast (if