including a bug where the cache could be corrupted upon certain access
    patterns. We also fixed a bug where the cache was being cleared due to a
    corrupted journal. We've added APIs to configure a request's `Cache-Control`
    headers, and to manually clear the cache.

 *  **Request cancellation fixes.** This update fixes a bug where synchronous

      object : Task("$okHttpName ConnectionPool connection opener") {
        override fun runOnce(): Long = openConnections(this@scheduleOpener)
      },
    )
  }

  /**
   * Holding the lock of the connection being added or removed when mutating this, and check its
   * [RealConnection.noNewExchanges] property. This defends against races where a connection is
   * simultaneously adopted and removed.
   */

  }

  /**
   * Returns an iterator over the cache's current entries. This iterator doesn't throw
   * `ConcurrentModificationException`, but if new entries are added while iterating, those new
   * entries will not be returned by the iterator. If existing entries are removed during iteration,
   * they will be absent (unless they were already returned).
   *

import okhttp3.internal.http2.Http2.FLAG_END_HEADERS
import okhttp3.internal.http2.Http2.FLAG_END_STREAM
import okhttp3.internal.http2.Http2.FLAG_NONE
import okhttp3.internal.http2.Http2.FLAG_PADDED
import okhttp3.internal.http2.Http2.FLAG_PRIORITY
import okhttp3.internal.http2.Http2.TYPE_GOAWAY
import okio.Buffer
import okio.BufferedSink
import okio.BufferedSource
import okio.ByteString

      } else {
        sslSocket.enabledProtocols
      }

    // In accordance with https://tools.ietf.org/html/draft-ietf-tls-downgrade-scsv-00 the SCSV
    // cipher is added to signal that a protocol fallback has taken place.
    val supportedCipherSuites = sslSocket.supportedCipherSuites
    val indexOfFallbackScsv =
      supportedCipherSuites.indexOf(
        "TLS_FALLBACK_SCSV",

When writing request headers, use `header(name, value)` to set the only occurrence of `name` to `value`. If there are existing values, they will be removed before the new value is added. Use `addHeader(name, value)` to add a header without removing the headers already present.

/**
 * Read and write HPACK v10.
 *
 * http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-12
 *
 * This implementation uses an array for the dynamic table and a list for indexed entries. Dynamic
 * entries are added to the array, starting in the last position moving forward. When the array
 * fills, it is doubled.
 */
@Suppress("NAME_SHADOWING")
object Hpack {
  private const val PREFIX_4_BITS = 0x0f