* forward to this implementation.
   */
  protected @Nullable Entry<K, V> standardFirstEntry() {
    return Iterables.<@Nullable Entry<K, V>>getFirst(entrySet(), null);
  }

  /**
   * A sensible definition of {@link #firstKey} in terms of {@code firstEntry}. If you override
   * {@code firstEntry}, you may wish to override {@code firstKey} to forward to this

                    appendJson("search-field", searchFieldMap, buf).append(',');
                    final Map<String, List<String>> requestHeaderMap = entity.getRequestHeaderList()
                            .stream()

    assertEquals("foo", Iterables.getFirst(iterable, "bar"));
  }

  public void testGetFirst_withDefault_empty() {
    Iterable<String> iterable = emptyList();
    assertEquals("bar", Iterables.getFirst(iterable, "bar"));
  }

  public void testGetFirst_withDefault_empty_null() {
    Iterable<String> iterable = emptyList();
    assertNull(Iterables.<@Nullable String>getFirst(iterable, null));
  }

                value = value.replace("${" + entry.getKey() + "}", entry.getValue());
            }
            return new Pair<>(key, value);
        }).collect(Collectors.toMap(Pair<String, String>::getFirst, Pair<String, String>::getSecond));
        final Map<String, String> configScriptMap = config.getHandlerScriptMap();

        initParamMap.putAll(configParamMap);
        final DataStoreParams paramMap = initParamMap;

            jspItems.add(new Pair<>(":" + p.getFirst(), "/" + p.getSecond()));
        }
        for (String key : ComponentUtil.getVirtualHostHelper().getVirtualHostPaths()) {
            if (StringUtil.isBlank(key)) {
                key = "/";
            }
            for (final Pair<String, String> p : systemHelper.getDesignJspFileNames()) {
                jspItems.add(new Pair<>(key + ":" + p.getFirst(), key + "/" + p.getSecond()));
            }

    assertEquals("foo", Iterables.getFirst(iterable, "bar"));
  }

  public void testGetFirst_withDefault_empty() {
    Iterable<String> iterable = emptyList();
    assertEquals("bar", Iterables.getFirst(iterable, "bar"));
  }

  public void testGetFirst_withDefault_empty_null() {
    Iterable<String> iterable = emptyList();
    assertNull(Iterables.<@Nullable String>getFirst(iterable, null));
  }

Set<String> caseInsensitiveSet = new CaseInsensitiveSet<>();

// Java 21 Sequenced Collections support
SequencedCollection<String> sequenced = CollectionsUtil.newLinkedHashSet();
String first = CollectionsUtil.getFirst(sequenced);
String last = CollectionsUtil.getLast(sequenced);
SequencedCollection<String> reversed = CollectionsUtil.reversed(sequenced);

// Specialized collections

            protected Map<String, String> getConfigPrameterMap(final ResponseData responseData, final ConfigName config) {
                return Map.of();
            }
        }.getChildUrlRules(null, null).map(v -> v.getFirst() + ":" + v.getSecond()).collect(Collectors.joining(",")));
        assertEquals("//A:href", new FessXpathTransformer() {

            }
        })));
        getQueryFieldConfig().additionalDefaultList.stream().forEach(f -> {
            final QueryBuilder query = builder.apply(f.getFirst(), f.getSecond());
            defaultQuery.add(query);
        });
        return defaultQuery;
    }

    /**
     * Creates a default query builder based on the configured query type.

   *
   * <p><b>Java 21+ users:</b> if {code iterable} is a {@code SequencedCollection} (e.g., any list),
   * consider using {@code collection.getFirst()} instead. Note that if the collection is empty,
   * {@code getFirst()} throws a {@code NoSuchElementException}, while this method returns the
   * default value.
   *
   * @param defaultValue the default value to return if the iterable is empty