## Declare `Header` parameters { #declare-header-parameters }

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

You can define the default value as well as all the extra validation or annotation parameters:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[9] *}

/// note | Technical Details

    public abstract RegularFileProperty getMetaDataFile();

    @OutputFile
    public abstract RegularFileProperty getMappingDestFile();

    /**
     * Package name can end with '.**' to exclude subpackages as well.
     */
    @Input
    public abstract SetProperty<String> getExcludedPackages();

    @TaskAction
    public void generate() throws IOException {

     */
    public static final int SID_FLAG_RESOLVE_SIDS = 0x0001;

    /**
     * Well known SID: EVERYONE (S-1-1-0).
     */
    public static SID EVERYONE = null;
    /**
     * Well known SID: CREATOR_OWNER (S-1-3-0).
     */
    public static SID CREATOR_OWNER = null;
    /**
     * Well known SID: SYSTEM (S-1-5-18).
     */
    public static SID SYSTEM = null;

    static {

	// to \. The conversion here rewrites / to \ and elides
	// . elements as well as trailing or duplicate separators. For
	// simplicity it avoids the conversion entirely for relative
	// paths or paths containing .. elements. For now,
	// \\server\share paths are not converted to
	// \\?\UNC\server\share paths because the rules for doing so
	// are less well-specified.
	if len(path) >= 2 && path[:2] == `\\` {

            //
            // 2. not to cancel any Future the user returned from an AsyncCallable
            //
            // We promise this because, once we cancel that Future, we would no longer be able to
            // tell when any underlying work it is doing is done. Thus, we might start a new task
            // while that underlying work is still running.
            //
            // So that is why we cancel only in the case of CAS success.

* <a href="https://x.com/tiangolo" class="external-link" target="_blank">Follow me on **X (Twitter)**</a> or <a href="https://fosstodon.org/@tiangolo" class="external-link" target="_blank">Mastodon</a>.
    * Tell me how you use FastAPI (I love to hear that).
    * Hear when I make announcements or release new tools.

			Optional:    true,
			Type:        "string",
		},
		config.HelpKV{
			Key:         ConfigURL,
			Description: `openid discovery document e.g. "https://accounts.google.com/.well-known/openid-configuration"` + defaultHelpPostfix(ConfigURL),
			Type:        "url",
		},
		config.HelpKV{
			Key:         ClientID,

 * under the License.
 */
package org.apache.maven.toolchain.io;

import java.io.IOException;

/**
 * Signals a failure to parse the toolchains due to invalid syntax (e.g. non well-formed XML or unknown elements).
 *
 * @since 3.3.0
 */
@Deprecated(since = "4.0.0")
public class ToolchainsParseException extends IOException {

    /**
     * The one-based index of the line containing the error.

For example, if you have a header parameter `save_data` in the code, the expected HTTP header will be `save-data`, and it will show up like that in the docs.

If for some reason you need to disable this automatic conversion, you can do it as well for Pydantic models for header parameters.

{* ../../docs_src/header_param_models/tutorial003_an_py310.py hl[19] *}

/// warning

  It hashes together all the branch names and hashes
  and then all the bookmark names and hashes.
  Tags are stored in .hgtags files in any of the branches,
  so the branch metadata includes the tags as well.
  """
  h = hashlib.sha256()
  peer = hg.peer(ui, {}, url)
  for name, revs in peer.branchmap().items():
    h.update(name)
    for r in revs:
      h.update(b' ')
      h.update(r)
    h.update(b'\n')