*/
internal sealed class Tags {
  /**
   * Returns a tags instance that maps [key] to [value]. If [value] is null, this returns a tags
   * instance that does not have any mapping for [key].
   */
  abstract fun <T : Any> plus(
    key: KClass<T>,
    value: T?,
  ): Tags

  abstract operator fun <T : Any> get(key: KClass<T>): T?
}

/** An empty tags. This is always the tail of a [LinkedTags] chain. */

		t.Fatalf("Should find 3 tags")
	}

	DB.Model(&blog2).Association("SharedTags").Find(&tags)
	if !compareTags(tags, []string{"tag1", "tag2", "tag3", "tag4"}) {
		t.Fatalf("Should find 3 tags")
	}

	// Replace
	tag5 := &Tag{Locale: "ZH", Value: "tag5"}
	tag6 := &Tag{Locale: "ZH", Value: "tag6"}
	DB.Model(&blog2).Association("SharedTags").Replace(tag5, tag6)
	var tags2 []Tag

        tags = PrunedTag.parse("a.test");
        assertEquals(1, tags.length);
        assertEquals("PrunedTag [tag=a, id=null, css=test, attrName=null, attrValue=null]", tags[0].toString());

        tags = PrunedTag.parse("a[target=_blank]");
        assertEquals(1, tags.length);
        assertEquals("PrunedTag [tag=a, id=null, css=null, attrName=target, attrValue=_blank]", tags[0].toString());

        List<String> fields = new ArrayList<>();
        fields.add("field1");
        List<String> tags = new ArrayList<>();
        tags.add("tag1");
        List<String> roles = new ArrayList<>();
        roles.add("role1");

        elevateWord = new ElevateWord(word, boost, readings, fields, tags, roles);

        // Check that we get the same references
        assertTrue(readings == elevateWord.getReadings());

        String[] tags1 = { "tag1", "tag2" };
        String[] tags2 = { "tag2", "tag1" };
        String[] roles = { "role1" };
        String[] fields = { "field1" };
        String[] excludes = { "exclude1" };

        String result1 = popularWordHelper.getCacheKey(seed, tags1, roles, fields, excludes);
        String result2 = popularWordHelper.getCacheKey(seed, tags2, roles, fields, excludes);

## Metadata for tags { #metadata-for-tags }

You can also add additional metadata for the different tags used to group your path operations with the parameter `openapi_tags`.

It takes a list containing one dictionary for each tag.

Each dictionary can contain:

* `name` (**required**): a `str` with the same tag name you use in the `tags` parameter in your *path operations* and `APIRouter`s.

        .plus(Boolean::class, null)
    assertThat(tags).isEqualTo(EmptyTags)
    assertThat(tags.toString()).isEqualTo("{}")
  }

  @Test
  fun removeAbsentFromEmpty() {
    val tags = EmptyTags.plus(String::class, null)
    assertThat(tags).isEqualTo(EmptyTags)
    assertThat(tags.toString()).isEqualTo("{}")
  }

  @Test
  fun removeAbsentFromNonEmpty() {
    val tags =
      EmptyTags

        String[] fields = { "field1", "field2" };
        item.setFields(fields);
        assertArrayEquals(fields, item.getFields());

        // Test tags
        String[] tags = { "tag1", "tag2" };
        item.setTags(tags);
        assertArrayEquals(tags, item.getTags());

        // Test roles
        String[] roles = { "admin", "user" };
        item.setRoles(roles);

		ilmNewerNoncurrentVersions = "ilm-newer-noncurrent-versions"
		ilmNoncurrentDays          = "ilm-noncurrent-days"
	)
	tags := make(map[string]string, 5)
	if src > lcEventSrc_None {
		tags[ilmSrc] = src.String()
	}
	tags[ilmAction] = event.Action.String()
	tags[ilmRuleID] = event.RuleID

	if !event.Due.IsZero() {
		tags[ilmDue] = event.Due.Format(iso8601Format)
	}

	// rule with Transition/NoncurrentVersionTransition in effect

     */
    public List<String> getWordList(final SearchRequestType searchRequestType, final String seed, final String[] tags, final String[] roles,
            final String[] fields, final String[] excludes) {
        final String baseSeed = seed != null ? seed : fessConfig.getSuggestPopularWordSeed();
        final String[] baseTags = tags != null ? tags : fessConfig.getSuggestPopularWordTagsAsArray();
        final String[] baseRoles = roles != null ? roles