Avant de définir `convert_underscores` sur `False`, gardez à l'esprit que certains proxies et serveurs HTTP interdisent l'utilisation d'en-têtes contenant des traits bas.

///

## Gérer les en-têtes dupliqués { #duplicate-headers }

Il est possible de recevoir des en-têtes en double. Autrement dit, le même en-tête avec plusieurs valeurs.

Vous pouvez définir ces cas à l'aide d'une liste dans la déclaration de type.

    }

    private static String parse(String rule, Set<String> dup) {
        String[] values = CSVUtil.parse(rule);
        if (dup.add(values[0]) == false) {
            throw new IllegalArgumentException("Found duplicate term [" + values[0] + "] in user dictionary.");
        }
        return rule;
    }

    public static UserDictionary getUserDictionary(Environment env, Settings settings) {

    testers.add(SetHashCodeTester.class);
    testers.add(SetEqualsTester.class);
    testers.add(SetRemoveTester.class);
    // SetRemoveAllTester doesn't exist because, Sets not permitting
    // duplicate elements, there are no tests for Set.removeAll() that aren't
    // covered by CollectionRemoveAllTester.
    return testers;
  }

  @Override
  protected List<TestSuite> createDerivedSuites(

{* ../../docs_src/header_params/tutorial002_an_py310.py hl[10] *}

/// warning | 警告

在將 `convert_underscores` 設為 `False` 之前，請注意有些 HTTP 代理與伺服器不允許使用帶有底線的標頭。

///

## 重複的標頭 { #duplicate-headers }

有時可能會收到重複的標頭，也就是同一個標頭會有多個值。

可以在型別宣告中使用 list 來定義這種情況。

你會以 Python 的 `list` 形式收到該重複標頭的所有值。

例如，要宣告可以出現多次的 `X-Token` 標頭，可以這樣寫：

{* ../../docs_src/header_params/tutorial003_an_py310.py hl[9] *}

    int NT_STATUS_PIPE_LISTENING = 0xC00000b3;
    /** The file that was specified is a directory */
    int NT_STATUS_FILE_IS_A_DIRECTORY = 0xC00000ba;
    /** A duplicate name exists on the network */
    int NT_STATUS_DUPLICATE_NAME = 0xC00000bd;
    /** The specified network name is no longer available */
    int NT_STATUS_NETWORK_NAME_DELETED = 0xC00000c9;

    int NT_STATUS_PIPE_LISTENING = 0xC00000b3;
    /** The file that was specified is a directory */
    int NT_STATUS_FILE_IS_A_DIRECTORY = 0xC00000ba;
    /** A duplicate name exists on the network */
    int NT_STATUS_DUPLICATE_NAME = 0xC00000bd;
    /** The specified network name is no longer available */
    int NT_STATUS_NETWORK_NAME_DELETED = 0xC00000c9;

            version = artifact.getBaseVersion();
        }

        // TODO also do this logging for other metadata?
        // TODO figure out way to avoid duplicated message
        if (getLogger().isDebugEnabled()) {
            if (!version.equals(artifact.getBaseVersion())) {
                String message = artifact.getArtifactId() + ": resolved to version " + version;

import java.util.ArrayDeque
import java.util.Deque
import javax.net.ssl.SSLPeerUnverifiedException

/**
 * A certificate chain cleaner that uses a set of trusted root certificates to build the trusted
 * chain. This class duplicates the clean chain building performed during the TLS handshake. We
 * prefer other mechanisms where they exist, such as with
 * [okhttp3.internal.platform.AndroidPlatform.AndroidCertificateChainCleaner].
 *

    return C2 * Integer.rotateLeft(hashCode * C1, 15);
  }

  private boolean checkFilter(int c) {
    return ((filter >> c) & 1) == 1;
  }

  // This is all essentially copied from ImmutableSet, but we have to duplicate because
  // of dependencies.

  // Represents how tightly we can pack things, as a maximum.
  private static final double DESIRED_LOAD_FACTOR = 0.5;

  /**

   *
   * <p>Because a {@code SetMultimap} has unique values for a given key, this method returns a
   * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
   *
   * <p>Any duplicates in {@code values} will be stored in the multimap once.
   */
  @CanIgnoreReturnValue
  @Override
  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {