'宣言 Public MustInherit Class ExtraMapLayerBuilder (Of T,TControl As ExtraMapLayer(Of T), TBuilder As ExtraMapLayerBuilder(Of T,TControl,TBuilder)) Inherits MapLayerBaseBuilder(Of T,TControl,TBuilder)
public abstract class ExtraMapLayerBuilder<T,TControl,TBuilder> : MapLayerBaseBuilder<T,TControl,TBuilder> where TControl: ExtraMapLayer<T> where TBuilder: ExtraMapLayerBuilder<T,TControl,TBuilder>