### Question:
StringNativeKind implements NativeKind { @Nullable public static NativeKind of(@Nullable String value) { if (value == null) { return null; } return new StringNativeKind(value); } StringNativeKind(String kind); @Nullable static NativeKind of(@Nullable String value); @Nullable static String toString(@Nullable NativeKind nativeKind); @Override String toString(); @Override boolean equals(Object other); @Override int hashCode();  }### Answer:
@Test public void constructor() { assertThat(new StringNativeKind("ast.Element")).isNotNull(); assertThat(StringNativeKind.of("ast.Element")).isNotNull(); assertThat(StringNativeKind.of(null)).isNull(); }