`Optional[str]` の`Optional` はFastAPIでは使用されていません（FastAPIは`str`の部分のみ使用します）。しかし、`Optional[str]` はエディタがコードのエラーを見つけるのを助けてくれます。

///

## Pydanticを使わない方法

   * or {@code 'A'} and {@code 'Z'} inclusive.
   *
   * <p>This method is significantly faster than {@link String#equalsIgnoreCase} and should be used
   * in preference if at least one of the parameters is known to contain only ASCII characters.
   *
   * <p>Note however that this method does not always behave identically to expressions such as:
   *
   * <ul>

  // webhook, for example, a cluster identifier.
  //
  // Attempting to use a user or basic auth e.g. "user:password@" is not
  // allowed. Fragments ("#...") and query parameters ("?...") are not
  // allowed, either.
  //
  // +optional
  optional string url = 3;

  // `service` is a reference to the service for this webhook. Either
  // `service` or `url` must be specified.

                .longOpt("ignore-transitive-repositories")
                .desc("If set, Maven will ignore remote repositories introduced by transitive dependencies.")
                .build());

        // Parameters handled by script
        options.addOption(Option.builder()
                .longOpt(DEBUG)
                .desc("Launch the JVM in debug mode (script option).")
                .build());

        final Map<String, String> paramMap = getHandlerParameterMap();

        final Map<String, Object> factoryParamMap = new HashMap<>();
        factory.setInitParameterMap(factoryParamMap);

        // parameters
        for (final Map.Entry<String, String> entry : paramMap.entrySet()) {
            final String key = entry.getKey();
            if (key.startsWith(CRAWLER_PARAM_PREFIX)) {

  private final double sumOfProductsOfDeltas;

  /**
   * Internal constructor. Users should use {@link PairedStatsAccumulator#snapshot}.
   *
   * <p>To ensure that the created instance obeys its contract, the parameters should satisfy the
   * following constraints. This is the callers responsibility and is not enforced here.
   *
   * <ul>
   *   <li>Both {@code xStats} and {@code yStats} must have the same {@code count}.

	_, errCode = extractSignedHeaders(signedHeaders, r)
	if errCode != ErrUnsignedHeaders {
		t.Fatalf("Expected the APIErrorCode to %d, but got %d", ErrUnsignedHeaders, errCode)
	}
	// set headers value through Get parameter
	inputQuery.Add("x-amz-server-side-encryption", xhttp.AmzEncryptionAES)
	r.URL.RawQuery = inputQuery.Encode()
	r.ParseForm()
	_, errCode = extractSignedHeaders(signedHeaders, r)
	if errCode != ErrNone {

	p := make([]*Type, len(dtype.ParamType))
	gp := make([]*ast.Field, len(dtype.ParamType))
	for i, f := range dtype.ParamType {
		// gcc's DWARF generator outputs a single DotDotDotType parameter for
		// function pointers that specify no parameters (e.g. void
		// (*__cgo_0)()).  Treat this special case as void. This case is
		// invalid according to ISO C anyway (i.e. void (*__cgo_1)(...) is not
		// legal).

  // name is the name of the given metric
  optional string name = 1;

  // selector is the string-encoded form of a standard kubernetes label selector for the given metric
  // When set, it is passed as an additional parameter to the metrics server for more specific metrics scoping.
  // When unset, just the metricName will be used to gather metrics.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.LabelSelector selector = 2;
}

`Generators` get as input the `Proxy` (a representation of the current client), the current `PushContext` snapshot, and a list of config updates that caused the change.