private val source: BufferedSource,
  private val callback: Callback,
) {
  private var lastId: String? = null

  interface Callback {
    fun onEvent(
      id: String?,
      type: String?,
      data: String,
    )

    fun onRetryChange(timeMs: Long)
  }

  /**
   * Process the next event. This will result in a single call to [Callback.onEvent] *unless* the

          responseCallback.onResponse(this@RealCall, response)
        } catch (e: IOException) {
          if (signalledCallback) {
            // Do not signal the callback twice!
            Platform.get().log("Callback failure for ${toLoggableString()}", Platform.INFO, e)
          } else {
            responseCallback.onFailure(this@RealCall, e)
          }
        } catch (t: Throwable) {
          cancel()

  private val call: Call?,
  private val request: Request,
  private val listener: EventSourceListener,
) : EventSource,
  ServerSentEventReader.Callback,
  Callback {
  constructor(call: Call, listener: EventSourceListener) : this(call, call.request(), listener)

  constructor(response: Response, listener: EventSourceListener) : this(null, response.request, listener)

  @Volatile private var canceled = false

import java.net.Socket
import java.net.SocketException
import java.util.concurrent.CompletableFuture
import java.util.concurrent.TimeUnit
import kotlin.test.assertFailsWith
import okhttp3.Call
import okhttp3.Callback
import okhttp3.DelegatingServerSocketFactory
import okhttp3.DelegatingSocketFactory
import okhttp3.OkHttpClient
import okhttp3.OkHttpClientTestRule
import okhttp3.Request
import okhttp3.RequestBody

        }
    }

    /**
     * Flushes configuration files to the search engine and executes a callback.
     *
     * @param callback the callback to execute after flushing
     */
    public void flushConfigFiles(final Runnable callback) {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();

        final String fesenType = fessConfig.getFesenType();

        }
      }
    ```

### Asynchronous Get ([.kt][AsynchronousGetKotlin], [.java][AsynchronousGetJava])

Download a file on a worker thread, and get called back when the response is readable. The callback is made after the response headers are ready. Reading the response body may still block. OkHttp doesn't currently offer asynchronous APIs to receive a response body in parts.

=== ":material-language-kotlin: Kotlin"
    ```kotlin

            </signature>
            <ignores>
              <!-- Unsafe isn't part of the documented Android API, but it is available.
                   And in cases where it's not, we have fallbacks (except maybe Striped64 (b/307807965)?). -->
              <ignore>sun.misc.Unsafe</ignore>
            </ignores>
          </configuration>
          <executions>
            <execution>