code: void removeEQ(Object o) {
          final ReentrantLock lock = this.lock;
          lock.lock();
          try {
              Object[] array = queue;
              for (int i = 0, n = size; i < n; i++) {
                  if (o == array[i]) {
                      removeAt(i);
                      break;
                  }
              }
          } finally {
              lock.unlock();
          }
      }
docs: Identity-based version for use in Itr.remove.