* readable name.
     */
    @CanIgnoreReturnValue
    public ToStringHelper addValue(@Nullable Object value) {
      return addHolder(value);
    }

    /**
     * Adds an unnamed value to the formatted output.
     *
     * <p>It is strongly encouraged to use {@link #add(String, boolean)} instead and give value a
     * readable name.
     *

 * should give up.
 *
 * When reactive authentication is requested by an origin web server, the response code is 401
 * and the implementation should respond with a new request that sets the "Authorization" header.
 *
 * ```java
 * if (response.request().header("Authorization") != null) {
 *   return null; // Give up, we've already failed to authenticate.
 * }
 *

     * readable name.
     */
    @CanIgnoreReturnValue
    public ToStringHelper addValue(@Nullable Object value) {
      return addHolder(value);
    }

    /**
     * Adds an unnamed value to the formatted output.
     *
     * <p>It is strongly encouraged to use {@link #add(String, boolean)} instead and give value a
     * readable name.
     *

# Advanced User Guide { #advanced-user-guide }

## Additional Features { #additional-features }

The main [Tutorial - User Guide](../tutorial/index.md){.internal-link target=_blank} should be enough to give you a tour through all the main features of **FastAPI**.

In the next sections you will see other options, configurations, and additional features.

/// tip

The next sections are **not necessarily "advanced"**.

        //
        // The request has not set any local or remote repositories as the system scoped dependency being resolved
        // should only
        // give us the dependency off the disk and nothing more.
        //
        request = new ArtifactResolutionRequest()
                .setArtifact(artifact)
                .setResolveRoot(true)

 */
@Experimental
public class VersionParserException extends MavenException {

    @Serial
    private static final long serialVersionUID = 1504740189114877333L;

    /**
     * @param message the message to give
     * @param e the {@link Exception}
     */
    public VersionParserException(String message, Exception e) {
        super(message, e);
    }

    @Serial
    private static final long serialVersionUID = -6259322450070320286L;

    public LookupException(String message) {
        super(message);
    }

    /**
     * @param message the message to give
     * @param e the {@link Exception}
     */
    public LookupException(String message, Exception e) {
        super(message, e);
    }

    /**
     * @param e the {@link Exception}
     */

 */
@Experimental
public class ProjectBuilderException extends MavenException {

    @Serial
    private static final long serialVersionUID = -7629871850875943799L;

    /**
     * @param message the message to give
     * @param e the {@link Exception}
     */
    public ProjectBuilderException(String message, Exception e) {
        super(message, e);
    }

 */
@Experimental
public class ToolchainManagerException extends MavenException {

    @Serial
    private static final long serialVersionUID = -9465854226608498L;

    /**
     * @param message the message to give
     * @param e the {@link Exception}
     */
    public ToolchainManagerException(String message, Exception e) {
        super(message, e);
    }

I'll tell you a bit more about these **concepts** here, and that would hopefully give you the **intuition** you would need to decide how to deploy your API in very different environments, possibly even in **future** ones that don't exist yet.

By considering these concepts, you will be able to **evaluate and design** the best way to deploy **your own APIs**.

In the next chapters, I'll give you more **concrete recipes** to deploy FastAPI applications.