public static Nazgul getInstance(NazgulName name) {
    return nazguls.get(name);
  }
@Test
  void testGetInstance() {
    for (final var name : NazgulName.values()) {
      final var nazgul = Nazgul.getInstance(name);
      assertNotNull(nazgul);
      assertSame(nazgul, Nazgul.getInstance(name));
      assertEquals(name, nazgul.getName());
    }
  }