* <li>File system crawling - crawls file systems and documents</li>
 * <li>Data store crawling - crawls databases and other data sources</li>
 * <li>Combined crawling - runs multiple crawling types simultaneously</li>
 * </ul>
 *
 * <p>Command line usage:
 * <pre>
 * java org.codelibs.fess.exec.Crawler [options...]
 *   -s, --sessionId sessionId     : Session ID for the crawling session

The same would happen if you had something like a <abbr title='A union between multiple types means "any of these types".'>union</abbr> between different types where one or more of them are not valid Pydantic types, for example this would fail 💥:

{* ../../docs_src/response_model/tutorial003_04_py310.py hl[8] *}

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Atualizar o App com Múltiplos Modelos { #update-the-app-with-multiple-models }

Agora vamos **refatorar** este app um pouco para aumentar a **segurança** e **versatilidade**.

     * this client silently recovers from the following problems:
     *
     * * **Unreachable IP addresses.** If the URL's host has multiple IP addresses,
     *   failure to reach any individual IP address doesn't fail the overall request. This can
     *   increase availability of multi-homed services.
     *

 * reduce contention. Method {@link #sum} (or, equivalently, {@link #longValue}) returns the current
 * total combined across the variables maintaining the sum.
 *
 * <p>This class is usually preferable to {@link AtomicLong} when multiple threads update a common
 * sum that is used for purposes such as collecting statistics, not for fine-grained synchronization
 * control. Under low update contention, the two classes have similar characteristics. But under

   * other {@code ClassValue} entries for the exception type to be tested. This lets us evaluate
   * whether our solution scales to use with multiple exception types and to whether it is affected
   * by other {@code ClassValue} users. Some of the benchmarked implementations don't use one or
   * both of these mechanisms, so they will be unaffected.
   */

///

## Ordem de execução de múltiplos middlewares { #multiple-middleware-execution-order }

                testPlugin = plugin;
            }

            Integer count = validPluginCounts.get(pluginArtifactId);

            assertEquals(0, (int) count, "Multiple copies of plugin: " + pluginArtifactId + " found in POM.");

            count = count + 1;

            validPluginCounts.put(pluginArtifactId, count);
        }

        assertNotNull(testPlugin);

        when(treeHandle.send(any(), any(), (RequestParam[]) any())).thenAnswer(invocation -> {
            return invocation.getArgument(1);
        });

        // When: Create iterator and close multiple times
        NetServerEnumIterator iterator = new NetServerEnumIterator(parent, treeHandle, "*", 0, null);

        iterator.close();
        iterator.close(); // Second close should be safe

 * #enqueue enqueueing} and then {@linkplain #dispatch dispatching} events.
 *
 * <p>The API of this class is designed to make it easy to achieve the following properties
 *
 * <ul>
 *   <li>Multiple events for the same listener are never dispatched concurrently.
 *   <li>Events for the different listeners are dispatched concurrently.
 *   <li>All events for a given listener dispatch on the provided executor.