return false; // This is the first occurrence
                    }
                })
                .toList();

        // Remove duplicates while preserving formatting
        duplicates.forEach(DomUtils::removeElement);

        return !duplicates.isEmpty();
    }

    private String createDependencyKey(Element dependency) {
        String groupId = dependency.childText(MavenPomElements.Elements.GROUP_ID);

):
    return [item, sub_item]


@app.post("/with-duplicates")
async def with_duplicates(item: Item, item2: Item = Depends(duplicate_dependency)):
    return [item, item2]


@app.post("/no-duplicates")
async def no_duplicates(item: Item, item2: Item = Depends(dependency)):
    return [item, item2]


@app.post("/with-duplicates-sub")
async def no_duplicates_sub(

    @SuppressWarnings("unchecked")
    E[] array = (E[]) elements.toArray();
    /*
     * For a Set, we guess that it contains no duplicates. That's just a guess for purpose of
     * sizing; if the Set uses different equality semantics, it might contain duplicates according
     * to equals(), and we will deduplicate those properly, albeit at some cost in allocations.
     */
    int expectedSize =

        assertEquals(cProject, sortedProjects.get(1));

        assertTrue(graph.getDownstreamProjects(aProject, false).contains(cProject));
    }

    // Test verifying that getDownstreamProjects does not contain duplicates.
    // This is a regression test for https://github.com/apache/maven/issues/2487.
    //
    // The graph is:
    // aProject -> bProject
    //        | -> dProject
    //        | -> eProject

        }
    }

    @Override
    public List<String> convert(final String text, final String field, final String... lang) throws IOException {
        // Use LinkedHashSet to maintain insertion order while eliminating duplicates
        final Set<String> resultSet = new LinkedHashSet<>();
        resultSet.add(text);

        // Start with the original text as the first input
        List<String> currentInputs = new ArrayList<>();

        assertEquals("https://example.com/sitemap2.xml", sitemaps[1]);
    }

    public void test_addSitemapNoDuplicates() {
        // Test that addSitemap doesn't add duplicates
        RobotsTxt robotsTxt = new RobotsTxt();

        robotsTxt.addSitemap("https://example.com/sitemap.xml");
        robotsTxt.addSitemap("https://example.com/sitemap.xml");

* `frozenset`:
    * In requests and responses, treated the same as a `set`:
        * In requests, a list will be read, eliminating duplicates and converting it to a `set`.
        * In responses, the `set` will be converted to a `list`.
        * The generated schema will specify that the `set` values are unique (using JSON Schema's `uniqueItems`).
* `bytes`:

Then we can declare `tags` as a set of strings:

{* ../../docs_src/body_nested_models/tutorial003_py310.py hl[12] *}

With this, even if you receive a request with duplicate data, it will be converted to a set of unique items.

And whenever you output that data, even if the source had duplicates, it will be output as a set of unique items.

And it will be annotated / documented accordingly too.

## Nested Models { #nested-models }

     * <p>This method performs the following validations:
     * <ul>
     *   <li>Allows null input (returns null)</li>
     *   <li>Ensures no duplicate repositories exist in the list</li>
     *   <li>Ensures no null repository entries exist in the list</li>
     * </ul>
     *
     * <p>Duplicate detection is based on the {@code RemoteRepository#equals(Object)}
     * method, which typically compares repository IDs and URLs.
     *

 * During this process only the most relevant version of each artifact
 * (based on group ID and artifact ID) is retained, resolving conflicts and eliminating duplicates to ensure
 * that each dependency is included only once in the final build.</p>
 *
 * <p><dfn>Dependency resolution</dfn> is the process of collecting dependencies, flattening the result graph,