}

/*
// RegisterStateless will register a stateless handler that serves
// []byte -> stream of ([]byte, error) requests.
func (m *Manager) RegisterStateless(id HandlerID, h StatelessHandler) error {
	if !id.valid() {
		return ErrUnknownHandler
	}
	if m.handlers.hasAny(id) && !id.isTestHandler() {
		return ErrHandlerAlreadyExists
	}

	m.handlers.stateless[id] = &h
	return nil
}
*/

 * resulting XML document is parsed, the parser API will return this text as the original literal
 * string {@code "Foo<Bar>"}.
 *
 * <p>An {@code Escaper} instance is required to be stateless, and safe when used concurrently by
 * multiple threads.
 *
 * <p>Because, in general, escaping operates on the code points of a string and not on its

### Service
- Inject behaviors (Bhv) for data access
- Use `OptionalEntity<T>` for nullable returns
- Plain classes (no extends/implements)

### Helper
- Stateless utility classes
- Access via `ComponentUtil.getXyzHelper()`
- Named with "Helper" suffix

### DBFlute Generated Code
```
opensearch/{index}/
├── bsentity/, bsbhv/    # Base classes (DO NOT EDIT)

	// StatelessHandlerFn must handle incoming stateless request.
	// A non-nil error value will be returned as RemoteErr(msg) to client.
	StatelessHandlerFn func(ctx context.Context, payload []byte, resp chan<- []byte) *RemoteErr

	// StatelessHandler is handlers for one to many requests,
	// where responses may be dropped.
	// Stateless requests provide no incoming stream and there is no flow control

	// message will be sent after the serialized message as little endian.
	FlagCRCxxh3 Flags = 1 << iota

	// FlagEOF the stream (either direction) is at EOF.
	FlagEOF

	// FlagStateless indicates the message is stateless.
	// This will retain clients across reconnections or
	// if sequence numbers are unexpected.
	FlagStateless

	// FlagPayloadIsErr can be used by individual ops to signify that

	// Stateless stream:
	if m.Flags&FlagStateless != 0 {
		// Reject for now, so we can safely add it later.
		if true {
			gridLogIf(ctx, c.queueMsg(m, muxConnectError{Error: "Stateless streams not supported"}))
			return
		}

		var handler *StatelessHandler
		if subID == nil {
			handler = c.handlers.stateless[m.Handler]
		} else {

 * resulting XML document is parsed, the parser API will return this text as the original literal
 * string {@code "Foo<Bar>"}.
 *
 * <p>A {@code CharEscaper} instance is required to be stateless, and safe when used concurrently by
 * multiple threads.
 *
 * <p>Popular escapers are defined as constants in classes like {@link
 * com.google.common.html.HtmlEscapers} and {@link com.google.common.xml.XmlEscapers}. To create

  /**
   * A strategy to translate T instances, to {@code numHashFunctions} bit indexes.
   *
   * <p>Implementations should be collections of pure functions (i.e. stateless).
   */
  interface Strategy extends Serializable {

    /**
     * Sets {@code numHashFunctions} bits of the given bit array, by hashing a user element.
     *

	cancelFn           context.CancelCauseFunc
	parent             *Connection
	respWait           chan<- Response
	respMu             sync.Mutex
	singleResp         bool
	closed             bool
	stateless          bool
	acked              bool
	init               bool
	deadline           time.Duration
	outBlock           chan struct{}
	subroute           *subHandlerID
	respErr            atomic.Pointer[error]

 * correctly if you are considering implementing a new escaper you should favor using UnicodeEscaper
 * wherever possible.
 *
 * <p>A {@code UnicodeEscaper} instance is required to be stateless, and safe when used concurrently
 * by multiple threads.
 *
 * <p>Popular escapers are defined as constants in classes like {@link
 * com.google.common.html.HtmlEscapers} and {@link com.google.common.xml.XmlEscapers}. To create