.add("\tkey\t:\tvalue\t") // '\t' also counts as whitespace
        .add("ping:  pong  ") // Value whitespace is trimmed.
        .add("kit:kat") // Space after colon is not required.
        .build()
    assertThat(headers.values("foo")).containsExactly("bar", "baz", "bak")
    assertThat(headers.values("key")).containsExactly("value")
    assertThat(headers.values("ping")).containsExactly("pong")

import org.opensearch.action.admin.cluster.health.ClusterHealthResponse;
import org.opensearch.cluster.health.ClusterHealthStatus;
import org.opensearch.common.xcontent.XContentType;

/**
 * Response entity for ping operations.
 */
public class PingResponse {
    private static final String CLUSTER_NAME = "cluster_name";
    private static final String STATUS = "status";
    private static final String TIMED_OUT = "timed_out";

    )
    val openAtNanos = System.nanoTime()
    newWebSocket()
    clientListener.assertOpen()
    clientListener.assertFailure(
      SocketTimeoutException::class.java,
      "sent ping but didn't receive pong within 500ms (after 0 successful ping/pongs)",
    )
    latch.countDown()
    val elapsedUntilFailure = System.nanoTime() - openAtNanos
    assertThat(TimeUnit.NANOSECONDS.toMillis(elapsedUntilFailure).toDouble())

      awaitingPong = true
    }

    if (failedPing != -1) {
      failWebSocket(
        e =
          SocketTimeoutException(
            "sent ping but didn't receive pong within " +
              "${pingIntervalMillis}ms (after ${failedPing - 1} successful ping/pongs)",
          ),
        isWriter = true,
      )
      return
    }

    try {
      writer.writePing(ByteString.EMPTY)

    assertThat(response.protocol).isEqualTo(protocol)

    // Confirm a single ping was sent and received, and its reply was sent and received.
    val logs = testLogHandler.takeAll()
    assertThat(countFrames(logs, "FINE: >> 0x00000000     8 PING          "))
      .isEqualTo(1)
    assertThat(countFrames(logs, "FINE: << 0x00000000     8 PING          "))
      .isEqualTo(1)

  // Masks are only a concern for client writers.
  private val maskKey: ByteArray? = if (isClient) ByteArray(4) else null
  private val maskCursor: Buffer.UnsafeCursor? = if (isClient) Buffer.UnsafeCursor() else null

  /** Send a ping with the supplied [payload]. */
  @Throws(IOException::class)
  fun writePing(payload: ByteString) {
    writeControlFrame(OPCODE_CONTROL_PING, payload)
  }

  /** Send a pong with the supplied [payload]. */

        sink.writeInt(settings[i])
      }
      sink.flush()
    }
  }

  /**
   * Send a connection-level ping to the peer. `ack` indicates this is a reply. The data in
   * `payload1` and `payload2` opaque binary, and there are no rules on the content.
   */
  @Throws(IOException::class)
  fun ping(
    ack: Boolean,
    payload1: Int,
    payload2: Int,
  ) {
    withLock {

     * Sets the interval between HTTP/2 and web socket pings initiated by this client. Use this to
     * automatically send ping frames until either the connection fails or it is closed. This keeps
     * the connection alive and may detect connectivity failures.
     *
     * If the server does not respond to each ping with a pong within `interval`, this client will

    }
  }

  @Test fun emptyPingCallsCallback() {
    data.write("8900".decodeHex()) // Empty ping
    clientReader.processNextFrame()
    callback.assertPing(EMPTY)
  }

  @Test fun pingCallsCallback() {
    data.write("890548656c6c6f".decodeHex()) // Ping with "Hello"
    clientReader.processNextFrame()
    callback.assertPing("Hello".encodeUtf8())
  }

    val settings1 = Settings()
    settings1[Settings.MAX_CONCURRENT_STREAMS] = maxConcurrentStreams
    peer.sendFrame().settings(settings1)
    peer.acceptFrame() // ACK
    peer.sendFrame().ping(false, 2, 0)
    peer.acceptFrame() // PING
    peer.play()

    // Play it back.
    val connection =
      Http2Connection
        .Builder(true, TaskRunner.INSTANCE)
        .socket(peer.openSocket().asBufferedSocket(), "peer")