The upcoming Android Studio runs in a JVM but has classes from Android and that confused OkHttp!

 *  Fix: Include the header `Accept: text/event-stream` for SSE calls. This header is not added if
    the request already contains an `Accept` header.

 *  Fix: Don't crash with a `NullPointerException` if a server sends a close while we're sending a
    ping. OkHttp had a race condition bug.


## Version 4.6.0

_2020-04-28_

import okhttp3.internal.isHealthy
import okhttp3.internal.tls.OkHostnameVerifier
import okhttp3.internal.ws.RealWebSocket
import okio.BufferedSink
import okio.BufferedSource

/**
 * A connection to a remote web server capable of carrying 1 or more concurrent streams.
 *
 * Connections are shared in a connection pool. Accesses to the connection's state must be guarded
 * by holding a lock on the connection.
 */
class RealConnection(

 * [DNS over HTTPS implementation][doh_spec].
 *
 * > A DNS API client encodes a single DNS query into an HTTP request
 * > using either the HTTP GET or POST method and the other requirements
 * > of this section.  The DNS API server defines the URI used by the
 * > request through the use of a URI Template.
 *
 * [doh_spec]: https://tools.ietf.org/html/draft-ietf-doh-dns-over-https-13
 */
class DnsOverHttps internal constructor(

 * the response, the client will issue a conditional `GET`. The server will then send either
 * the updated response if it has changed, or a short 'not modified' response if the client's copy
 * is still valid. Such responses increment both the network count and hit count.
 *
 * The best way to improve the cache hit rate is by configuring the web server to return cacheable

  private fun setLevel(level: Level) {
    networkInterceptor.setLevel(level)
    applicationInterceptor.setLevel(level)
  }

  @BeforeEach
  fun setUp(server: MockWebServer) {
    this.server = server
    client =
      OkHttpClient.Builder()
        .addNetworkInterceptor(
          Interceptor { chain ->
            when {

import okio.BufferedSource
import okio.buffer
import okio.sink
import okio.source

/**
 * A single attempt to connect to a remote server, including these steps:
 *
 *  * [TCP handshake][connectSocket]
 *  * Optional [CONNECT tunnels][connectTunnel]. When using an HTTP proxy to reach an HTTPS server
 *    we must send a `CONNECT` request, and handle authorization challenges from the proxy.
 *  * Optional [TLS handshake][connectTls].
 *

  val platform = PlatformRule()
  private lateinit var server: MockWebServer
  private lateinit var dns: Dns
  private val cacheFs = FakeFileSystem()
  private val bootstrapClient =
    OkHttpClient.Builder()
      .protocols(listOf(Protocol.HTTP_2, Protocol.HTTP_1_1))
      .build()

  @BeforeEach
  fun setUp(server: MockWebServer) {
    this.server = server
    server.protocols = bootstrapClient.protocols

    val address = factory.newAddress()
    proxySelector.proxies.add(Proxy.NO_PROXY)
    val routeSelector = newRouteSelector(address)
    proxySelector.assertRequests(address.url.toUri())

    // Only the origin server will be attempted.
    assertThat(routeSelector.hasNext()).isTrue()
    dns[uriHost] = dns.allocate(1)
    val selection = routeSelector.next()

    open fun url(url: URL) = url(url.toString().toHttpUrl())

    /**
     * Sets the header named [name] to [value]. If this request already has any headers
     * with that name, they are all replaced.
     */
    open fun header(
      name: String,
      value: String,
    ) = commonHeader(name, value)

    /**
     * Adds a header with [name] and [value]. Prefer this method for multiply-valued
     * headers like "Cookie".

    assertThat(webSocket.receivedPongCount()).isEqualTo(0)
    assertThat(server.sentPingCount()).isEqualTo(0)
    assertThat(server.receivedPingCount()).isEqualTo(0)
    assertThat(server.receivedPongCount()).isEqualTo(0)
    closeWebSockets(webSocket, server)
  }

  /**
   * Configure the websocket to send pings every 500 ms. Artificially prevent the server from