class in UnityEditor.Search
인터페이스 구현:IEventHandler, IExperimentalFeatures, IResolvedStyle, ITransform, ITransitionAnimations, IVisualElementScheduler
A query block is the visual element of a query node in a query.
In example, shader=lit will be a query filter block with QueryBlock.name equal to shader, QueryBlock.value equal to lit and the QueryBlock.op equal to =.