}

    @Override
    public Set<E> create(Object... elements) {
      Object[] duplicated = new Object[elements.length * 2];
      for (int i = 0; i < elements.length; i++) {
        duplicated[i] = elements[i];
        duplicated[i + elements.length] = elements[i];
      }
      return ((Multiset<E>) gen.create(duplicated)).elementSet();
    }

    @Override
    public E[] createArray(int length) {

            if (arMap.containsKey(accessResult.getUrl())) {
                throw new CrawlerSystemException(
                        "AccessResult for URL '" + accessResult.getUrl() + "' already exists. Duplicate URLs are not allowed.");
            }
            arMap.put(accessResult.getUrl(), accessResult);
        }

    }

    /**
     * Gets the count of access results for the specified session.
     *

func (c Config) GetDestination() Destination {
	if len(c.Rules) > 0 {
		return c.Rules[0].Destination
	}
	return Destination{}
}

// Replicate returns true if the object should be replicated.
func (c Config) Replicate(obj ObjectOpts) bool {
	for _, rule := range c.FilterActionableRules(obj) {
		if rule.Status == Disabled {
			continue
		}

          else -> readToken()
        } ?: return // Expected a value.

      val replaced = parameters.put(peek, parameterValue)
      peek = null
      if (replaced != null) return // Unexpected duplicate parameter.
      if (!skipCommasAndWhitespace() && !exhausted()) return // Expected ',' or EOF.
    }
    result.add(Challenge(schemeName, parameters))
  }
}

/** Returns true if any commas were skipped. */

 *
 * <p>When iterating through the collections supplied by this class, the ordering of values for a
 * given key agrees with the order in which the values were added.
 *
 * <p>This multimap allows duplicate key-value pairs. After adding a new key-value pair equal to an
 * existing key-value pair, the {@code ArrayListMultimap} will contain entries for both the new
 * value and the old value.
 *

        return cache.computeIfAbsent(key, k -> new CacheRecord(exception));
    }

    protected void assertUniqueKey(Key key) {
        if (cache.containsKey(key)) {
            throw new IllegalStateException("Duplicate artifact resolution result for project " + key);
        }
    }

    @Override
    public void flush() {
        cache.clear();
    }

    @Override

    // my best guess is that the jdk authors have spent more time optimizing that callpath than this
    // one. (StringCoding$StringDecoder vs. StreamDecoder).  StringCoding has a ton of special cases
    // theoretically we could duplicate all that logic here to try to beat 'new String' or at least
    // come close.
    USING_DECODER_WITH_SIZE_HINT {
      @Override
      String read(ByteSource byteSource, Charset cs) throws IOException {

                    new ContentNotFoundException(urlQueue.getParentUrl(), url));
        }
    }

    /**
     * Stores a child URL in the crawling queue with duplicate host handling.
     * This method applies duplicate host conversion before storing the URL.
     *
     * @param childUrl the child URL to store
     * @param parentUrl the parent URL that referenced this child URL

    @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 =

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 }