"paid": true
}
```

and it would expect a response from that *external API* with a JSON body like:

```JSON
{
    "ok": true
}
```

/// tip

Notice how the callback URL used contains the URL received as a query parameter in `callback_url` (`https://www.external.org/events`) and also the invoice `id` from inside of the JSON body (`2expen51ve`).

///

On startup all remote servers must be specified.
From that individual connections will be spawned to each remote server,
or incoming requests will be hooked up to the appropriate connection.

To get a connection to a specific server, use `Manager.Connection(host)` to get a connection to the specified host.
From this connection individual requests can be made.

    /**
     * Gets the configured LLM type.
     *
     * @return the LLM type from configuration
     */
    protected abstract String getLlmType();

    /**
     * Gets the configuration prefix for this provider.
     * Used to look up per-prompt-type parameters from FessConfig.
     *
     * @return the config prefix (e.g. "rag.llm.openai")
     */

import okio.ByteString.Companion.encodeUtf8

object Http2 {
  @JvmField
  val CONNECTION_PREFACE = "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n".encodeUtf8()

  /** The initial max frame size, applied independently writing to, or reading from the peer. */
  const val INITIAL_MAX_FRAME_SIZE = 0x4000 // 16384

  const val TYPE_DATA = 0x0
  const val TYPE_HEADERS = 0x1
  const val TYPE_PRIORITY = 0x2
  const val TYPE_RST_STREAM = 0x3

    try (OutputStream out = openStream()) {
      out.write(bytes);
    }
  }

  /**
   * Writes all the bytes from the given {@code InputStream} to this sink. Does not close {@code
   * input}.
   *
   * @return the number of bytes written
   * @throws IOException if an I/O occurs while reading from {@code input} or writing to this sink
   */
  @CanIgnoreReturnValue

################################################################################
ARG BASE_IMAGE=ubuntu:22.04@sha256:445586e41c1de7dfda82d2637f5ff688deea9eb5f5812f8c145afacc35b9f0db
FROM $BASE_IMAGE AS devel
# See https://docs.docker.com/reference/dockerfile/#understand-how-arg-and-from-interact
# on why we cannot reference BASE_IMAGE again unless we declare it again.
################################################################################

     * environment.
     */
    public Type3Message() {
        setFlags(getDefaultFlags());
        setDomain(getDefaultDomain());
        setUser(getDefaultUser());
        setWorkstation(getDefaultWorkstation());
    }

    /**
     * Creates a Type-3 message in response to the given Type-2 message
     * using default values from the current environment.
     *

        }
      }
      assertThat(service.state()).isNotEqualTo(from);
    }

    @Override
    public synchronized void terminated(State from) {
      assertEquals(from, Iterables.getLast(stateHistory, State.NEW));
      stateHistory.add(State.TERMINATED);
      assertEquals(State.TERMINATED, service.state());
      if (from == State.NEW) {
        try {
          service.awaitRunning();
          fail();

   *
   * Here is an example of storedPermitsToWaitTime: If storedPermits == 10.0, and we want 3 permits,
   * we take them from storedPermits, reducing them to 7.0, and compute the throttling for these as
   * a call to storedPermitsToWaitTime(storedPermits = 10.0, permitsToTake = 3.0), which will
   * evaluate the integral of the function from 7.0 to 10.0.
   *
   * Using integrals guarantees that the effect of a single acquire(3) is equivalent to {

        }
      }
      assertThat(service.state()).isNotEqualTo(from);
    }

    @Override
    public synchronized void terminated(State from) {
      assertEquals(from, Iterables.getLast(stateHistory, State.NEW));
      stateHistory.add(State.TERMINATED);
      assertEquals(State.TERMINATED, service.state());
      if (from == State.NEW) {
        try {
          service.awaitRunning();
          fail();