### Use cases: external service

An example could be that you have an external authentication provider that you need to call.

You send it a token and it returns an authenticated user.

    // System.identityHashCode, which means the assignment of keys to segments is nondeterministic,
    // so more than (maximumSize / #segments) keys could get assigned to the same segment, which
    // would cause one to be evicted.
    return new CacheBuilderFactory()
        .withKeyStrengths(ImmutableSet.of(Strength.STRONG, Strength.WEAK))

        }
        try {
            new JavaParser().parse(sourceFile).getResult().get().accept(new SourceMetaDataVisitor(), repository)
        } catch (Exception e) {
            throw new DocGenerationException("Could not parse '$sourceFile'.", e)
        }
    }

    def fullyQualifyAllTypeNames(gradlebuild.docs.dsl.source.model.ClassMetaData classMetaData, TypeNameResolver resolver) {
        try {

      Stopwatch s = Stopwatch.createStarted();
      // here is where you would do something
      total += s.elapsed(NANOSECONDS);
    }
    return total;
  }

  @Benchmark
  long manual(int reps) {
    long total = 0;
    for (int i = 0; i < reps; i++) {
      long start = System.nanoTime();
      // here is where you would do something
      total += (System.nanoTime() - start);
    }
    return total;
  }

///

/// info

To declare headers, you need to use `Header`, because otherwise the parameters would be interpreted as query parameters.

///

## Automatic conversion

`Header` has a little extra functionality on top of what `Path`, `Query` and `Cookie` provide.

			portForwarder, err := client.NewPortForwarder(podName, ns, "", 0, controlzPort)
			if err != nil {
				return fmt.Errorf("could not build port forwarder for ControlZ %s: %v", podName, err)
			}
			defer portForwarder.Close()
			err = portForwarder.Start()
			if err != nil {
				return fmt.Errorf("could not start port forwarder for ControlZ %s: %v", podName, err)
			}

			ctrlzClient := &ControlzClient{
				baseURL: &url.URL{

        }

        final ExtractorFactory extractorFactory = crawlerContainer.getComponent("extractorFactory");
        if (extractorFactory == null) {
            throw new CrawlerSystemException("Could not find extractorFactory.");
        }
        final Extractor extractor = extractorFactory.getExtractor(responseData.getMimeType());
        final Map<String, String> params = new HashMap<>();

      // permitted not to throw because it would be a no-op
    }
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEY_QUERIES)
  public void testReplace_absentNullKeyUnsupported() {
    try {
      getMap().replace(null, v3());
    } catch (NullPointerException tolerated) {
      // permitted not to throw because it would be a no-op
    }
    expectUnchanged();
  }

        MAX_FD=$( ulimit -H -n ) ||
            warn "Could not query maximum file descriptor limit"
    esac
    case $MAX_FD in  #(
      '' | soft) :;; #(
      *)
        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
        # shellcheck disable=SC2039,SC3045
        ulimit -n "$MAX_FD" ||
            warn "Could not set maximum file descriptor limit to $MAX_FD"
    esac
fi

    public MimeTypeHelperImpl() {
        try {
            mimeTypes = MimeTypesFactory.create(MIME_TYPES_RESOURCE_NAME);
        } catch (final Exception e) {
            throw new CrawlerSystemException("Could not initialize MimeTypeHelper.", e);
        }
    }

    @Override
    public String getContentType(final InputStream is, final String filename) {
        final Map<String, String> params = new HashMap<>();