Previously if you configured a ping interval that would cause OkHttp to send
    pings, but it did not track whether the reply pongs were received. With this
    update OkHttp requires that every ping receive a response: if it does not
    the connection will be closed and the listener's `onFailure()` method will
    be called.

    Web sockets have always been had pings, but pings on HTTP/2 connections is

    peer.sendFrame().ping(false, 2, 3)
    peer.acceptFrame() // PING
    peer.play()

    // Play it back.
    connect(peer)

    // Verify the peer received what was expected.
    val ping = peer.takeFrame()
    assertThat(ping.type).isEqualTo(Http2.TYPE_PING)
    assertThat(ping.streamId).isEqualTo(0)
    assertThat(ping.payload1).isEqualTo(2)
    assertThat(ping.payload2).isEqualTo(3)

    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)

				{Name: "Asia/India/Karnataka/Bangalore/Koramangala/pics"},
				{Name: "newPrefix0"},
				{Name: "newPrefix1"},
				{Name: "newzen/zen/recurse/again/again/again/pics"},
				{Name: "obj0"},
				{Name: "obj1"},
				{Name: "obj2"},
			},
		},
		// ListObjectsResult-16.
		// Marker is set to "Asia/India/Karnataka/Bangalore/Koramangala/pics" in the testCase, (testCase 41).
		16: {
			IsTruncated: false,

            final PingResponse pingResponse = searchEngineClient.ping();
            writeJsonResponse(pingResponse.getStatus() == 0 ? HttpServletResponse.SC_OK : HttpServletResponse.SC_SERVICE_UNAVAILABLE,
                    "\"data\":" + pingResponse.getMessage());
        } catch (final Exception e) {
            if (logger.isDebugEnabled()) {
                logger.debug("Failed to process a ping request.", e);
            }

          "interval": "1m",
          "legendFormat": "{{server}}",
          "refId": "A"
        }
      ],
      "title": "Backlog (last 5 mins)",
      "type": "timeseries"
    },
    {
      "datasource": {
        "type": "prometheus",
        "uid": "${DS_PROMETHEUS}"
      },
      "fieldConfig": {
        "defaults": {

```
mc cp myphoto.jpg myminio/images
```

In the previous terminal, you will now see the operation that MinIO performs on Redis:

```
127.0.0.1:6379> monitor
OK
1490686879.650649 [0 172.17.0.1:44710] "PING"

				"application/onenote",
				"application/parityfec",
				"application/patch-ops-error+xml",
				"application/pgp-encrypted",
				"application/pgp-keys",
				"application/pgp-signature",
				"application/pics-rules",
				"application/pidf+xml",
				"application/pidf-diff+xml",
				"application/pkcs10",
				"application/pkcs7-mime",
				"application/pkcs7-signature",
				"application/pkix-cert",