@Override
    public E removeFirst() {
      synchronized (mutex) {
        return delegate().removeFirst();
      }
    }

    @Override
    public E removeLast() {
      synchronized (mutex) {
        return delegate().removeLast();
      }
    }

    @Override
    @CheckForNull
    public E pollFirst() {
      synchronized (mutex) {
        return delegate().pollFirst();

    @Override
    public E removeFirst() {
      synchronized (mutex) {
        return delegate().removeFirst();
      }
    }

    @Override
    public E removeLast() {
      synchronized (mutex) {
        return delegate().removeLast();
      }
    }

    @Override
    @CheckForNull
    public E pollFirst() {
      synchronized (mutex) {
        return delegate().pollFirst();

          if (topConcat.metaIterators != null) {
            while (!topConcat.metaIterators.isEmpty()) {
              this.metaIterators.addFirst(topConcat.metaIterators.removeLast());
            }
          }
          this.topMetaIterator = topConcat.topMetaIterator;
        }
      }
      return true;
    }

    @Override
    @ParametricNullness

      for (i in encodedQueryNamesAndValues!!.size - 2 downTo 0 step 2) {
        if (canonicalName == encodedQueryNamesAndValues!![i]) {
          encodedQueryNamesAndValues!!.removeAt(i + 1)
          encodedQueryNamesAndValues!!.removeAt(i)
          if (encodedQueryNamesAndValues!!.isEmpty()) {
            encodedQueryNamesAndValues = null
            return
          }
        }
      }
    }

    val events = mutableListOf<Any>()

    @Synchronized fun takeEvent(): Any {
      while (events.isEmpty()) {
        wait()
      }
      return events.removeAt(0)
    }

    @Synchronized override fun onRequest(
      streamId: Int,
      requestHeaders: List<Header>,
    ): Boolean {
      assertThat(streamId).isEqualTo(2)