// clear absent
    assertFalse(segment.clearValueForTesting(key, hash, valueRef));

    segment.setTableEntryForTesting(0, entry);
    // don't increment count; this is used during computation
    assertTrue(segment.clearValueForTesting(key, hash, valueRef));
    // no notification sent with clearValue
    assertEquals(0, segment.count);

    // clear absent
    assertFalse(segment.clearValueForTesting(key, hash, valueRef));

    segment.setTableEntryForTesting(0, entry);
    // don't increment count; this is used during computation
    assertTrue(segment.clearValueForTesting(key, hash, valueRef));
    // no notification sent with clearValue
    assertEquals(0, segment.count);

      } finally {
        unlock();
      }
    }

    /** Clears a value that has not yet been set, and thus does not require count to be modified. */
    @CanIgnoreReturnValue
    boolean clearValueForTesting(
        K key,
        int hash,
        WeakValueReference<K, V, ? extends InternalEntry<K, V, ?>> valueReference) {
      lock();
      try {
        AtomicReferenceArray<E> table = this.table;