* A collector that converts a stream of zero or one elements to an {@code Optional}.
   *
   * @throws IllegalArgumentException if the stream consists of two or more elements.
   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.
   */

     * <ul>
     * <li><code>1.0</code> Version 1.0 as a recommended version</li>
     * <li><code>[1.0]</code> Version 1.0 explicitly only</li>
     * <li><code>[1.0,2.0)</code> Versions 1.0 (included) to 2.0 (not included)</li>
     * <li><code>[1.0,2.0]</code> Versions 1.0 to 2.0 (both included)</li>
     * <li><code>[1.5,)</code> Versions 1.5 and higher</li>

 * #setException(Throwable)} or {@link #setFuture(ListenableFuture)} call. It can also, like any
 * other {@code Future}, be {@linkplain #cancel cancelled}.
 *
 * <p>{@code SettableFuture} is the recommended {@code ListenableFuture} implementation when your
 * task cannot be implemented with {@link ListeningExecutorService}, the various {@link Futures}

     *
     * @return The global toolchains source or {@code null} if none.
     */
    Source getGlobalToolchainsSource();

    /**
     * Sets the global toolchains source. If both user toolchains and a global toolchains are given, the user toolchains
     * take precedence.
     *
     * @param globalToolchainsSource The global toolchains source, may be {@code null} to disable global toolchains.

 * which is optimal, and <i>not</i> the size of the internal hashtable, which could be much larger
 * than {@code size()}. Furthermore, this structure only depends on a fixed number of arrays; {@code
 * add(x)} operations <i>do not</i> create objects for the garbage collector to deal with, and for
 * every element added, the garbage collector will have to traverse {@code 1.5} references on

     * @param model The model to validate, must not be {@code null}.
     * @param request The model building request that holds further settings, must not be {@code null}.
     * @param problems The container used to collect problems that were encountered, must not be {@code null}.
     * @since 4.0.0
     */
    default void validateExternalProfiles(

 * Represents the packaging of a Maven project.
 *
 * <p>The {@code Packaging} class defines the type of artifact that a Maven project produces during the build process.
 * The packaging type determines the structure of the project's output and how Maven will treat the resulting artifact.</p>
 *
 * <p>Common packaging types include {@code jar}, {@code war}, {@code pom}, {@code maven-plugin}, {@code ear}, and others.

  /**
   * Returns a collection that applies {@code function} to each element of {@code fromCollection}.
   * The returned collection is a live view of {@code fromCollection}; changes to one affect the
   * other.
   *
   * <p>The returned collection's {@code add()} and {@code addAll()} methods throw an {@link
   * UnsupportedOperationException}. All other collection methods are supported, as long as {@code
   * fromCollection} supports them.
   *

  /**
   * Flush a {@link Flushable}, with control over whether an {@code IOException} may be thrown.
   *
   * <p>If {@code swallowIOException} is true, then we don't rethrow {@code IOException}, but merely
   * log it.
   *
   * @param flushable the {@code Flushable} object to be flushed.
   * @param swallowIOException if true, don't propagate IO exceptions thrown by the {@code flush}
   *     method

# Dependencies with yield

FastAPI supports dependencies that do some <abbr title='sometimes also called "exit code", "cleanup code", "teardown code", "closing code", "context manager exit code", etc.'>extra steps after finishing</abbr>.

To do this, use `yield` instead of `return`, and write the extra steps (code) after.

/// tip

Make sure to use `yield` one single time per dependency.

///

/// note | "Technical Details"