protected static final Pattern USER_AGENT_RECORD =
            Pattern.compile("^user-agent:\\s*([^\\t\\n\\x0B\\f\\r]+)\\s*$", Pattern.CASE_INSENSITIVE);

    protected static final Pattern DISALLOW_RECORD = Pattern.compile("^disallow:\\s*([^\\s]*)\\s*$", Pattern.CASE_INSENSITIVE);

    protected static final Pattern ALLOW_RECORD = Pattern.compile("^allow:\\s*([^\\s]*)\\s*$", Pattern.CASE_INSENSITIVE);

		if r.Destination.LegacyArn() {
			legacyArn = true
		}
		if c.RoleArn == "" && !r.Destination.TargetArn() {
			return errDestinationArnMissing
		}
	}
	// disallow combining old replication configuration which used RoleArn as target ARN with multiple
	// destination replication
	if c.RoleArn != "" && len(targetMap) > 1 {
		return errRoleArnPresentForMultipleTargets
	}

            path = path.replace("\\", "/");
            // ---------------------------------------------------------------------------------
            // I'm not sure if this last regexp was really intended to disallow the usage of
            // network paths as user.home directory. Unfortunately it did. I removed it and
            // have not detected any problems yet.

```Python hl_lines="10"
{!> ../../docs_src/header_params/tutorial002.py!}
```

////

/// warning

Before setting `convert_underscores` to `False`, bear in mind that some HTTP proxies and servers disallow the usage of headers with underscores.

///

## Duplicate headers

It is possible to receive duplicate headers. That means, the same header with multiple values.

 public:
  AbstractOperationKind getKind() const { return kind_; }

  // Release any underlying resources, including the interface object.
  //
  // WARNING: The destructor of this class is marked as protected to disallow
  // clients from directly destroying this object since it may manage it's own
  // lifetime through ref counting. Thus this must be allocated on the heap and

		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
		return
	}

	var ignoreInUse bool
	if forceStr := r.Form.Get("force"); forceStr != "" {
		ignoreInUse, _ = strconv.ParseBool(forceStr)
	}

	// Disallow remote tiers with internal storage class names
	switch cfg.Name {
	case storageclass.STANDARD, storageclass.RRS:
		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, errTierReservedName), r.URL)
		return
	}

				return mode, retainDate, legalHold, ErrObjectLocked
			}
			mode = r.Mode
			retainDate = r.RetainUntilDate
			legalHold = objectlock.GetObjectLegalHoldMeta(objInfo.UserDefined)
			// Disallow overwriting an object on legal hold
			if legalHold.Status == objectlock.LegalHoldOn {
				return mode, retainDate, legalHold, ErrObjectLocked
			}
		}
	}

	if legalHoldRequested {
		var lerr error

  // Healthy pods will be subject to the PDB for eviction.
  //
  // Additional policies may be added in the future.
  // Clients making eviction decisions should disallow eviction of unhealthy pods
  // if they encounter an unrecognized policy in this field.
  //
  // This field is beta-level. The eviction API uses this field when

   *
   * <p>URI formatting requires that IPv6 literals be surrounded by brackets, like "[2001:db8::1]".
   * Chain this call after {@link #fromString(String)} to increase the strictness of the parser, and
   * disallow IPv6 literals that don't contain these brackets.
   *
   * <p>Note that this parser identifies IPv6 literals solely based on the presence of a colon. To

    }
  }

  private void doTestExistsThrowsSecurityException() throws IOException, URISyntaxException {
    File file = null;
    // In Java 9, Logger may read the TZ database. Only disallow reading the class path URLs.
    final PermissionCollection readClassPathFiles =
        new FilePermission("", "read").newPermissionCollection();
    for (URL url : ClassPath.parseJavaClassPath()) {