unity client compile error - AsyncObjectQueue does not contain a definition for Clear - _queue.Clear();

[Molder72]

when you try to compile one of the demo projects (EuNet-Starter or EuNet-Tanks) appears the error. only when you compile in unity not when only play

Library\PackageCache\com.zestylife.eunet@f63a5360f4\Runtime\EuNet.Core\Util\AsyncObjectQueue.cs(20,20): error CS1061: 'ConcurrentQueue<T>' does not contain a definition for 'Clear' and no accessible extension method 'Clear' accepting a first argument of type 'ConcurrentQueue<T>' could be found (are you missing a using directive or an assembly reference?)

in the class AsyncObjectQueue, _queue.Clear(); give an error