CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder().ticker(testTicker);
    assertThrows(IllegalStateException.class, () -> builder.ticker(testTicker));
  }

  public void testRemovalListener_setTwice() {
    RemovalListener<Object, Object> testListener = nullRemovalListener();
    CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder().removalListener(testListener);