internal fun Response.headersContentLength(): Long {
  return headers["Content-Length"]?.toLongOrDefault(-1L) ?: -1L
}

/** Returns an immutable copy of this. */
internal fun <T> List<T>.toImmutableList(): List<T> {
  return Collections.unmodifiableList(toMutableList())
}

/** Returns an immutable list containing [elements]. */
@SafeVarargs
internal fun <T> immutableListOf(vararg elements: T): List<T> {

import okhttp3.internal.http2.Http2Stream
import okhttp3.internal.immutableListOf
import okhttp3.internal.platform.Platform
import okhttp3.internal.threadFactory
import okhttp3.internal.toImmutableList
import okhttp3.internal.ws.RealWebSocket
import okhttp3.internal.ws.WebSocketExtensions
import okhttp3.internal.ws.WebSocketProtocol
import okio.Buffer
import okio.BufferedSink
import okio.BufferedSource

      fail("Expected NPE");
    } catch (NullPointerException expected) {
    }
  }

  public void testToImmutableList() {
    CollectorTester.of(ImmutableList.<String>toImmutableList())
        .expectCollects(ImmutableList.of("a", "b", "c", "d"), "a", "b", "c", "d");
  }

  // Basic tests

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester

   *
   * <pre>
   * {@code @SuppressWarnings("unchecked") // safe because of ::isInstance check
   * ImmutableList<NewType> result =
   *     (ImmutableList) stream.filter(NewType.class::isInstance).collect(toImmutableList());}
   * </pre>
   */
  @SuppressWarnings("unchecked")
  @GwtIncompatible // Class.isInstance
  public static <T> Iterable<T> filter(final Iterable<?> unfiltered, final Class<T> desiredType) {

   *
   * <pre>
   * {@code @SuppressWarnings("unchecked") // safe because of ::isInstance check
   * ImmutableList<NewType> result =
   *     (ImmutableList) stream.filter(NewType.class::isInstance).collect(toImmutableList());}
   * </pre>
   */
  @SuppressWarnings("unchecked")
  @GwtIncompatible // Class.isInstance
  public static <T> Iterable<T> filter(final Iterable<?> unfiltered, final Class<T> desiredType) {