DynamoVisualProgramming.DynamoServices by Autodesk

<PackageReference Include="DynamoVisualProgramming.DynamoServices" Version="3.3.0-beta6200" />

 ExtensionApplicationAttribute

This attribute is used to specify the Type of class that implements IExtensionApplication interface in the specified assembly. This attribute can be used only once at assembly level. Having this attribute saves the cost of reflection on each exported types to find the type that implements IExtensionApplication interface.
public Type Type { get; }

public ExtensionApplicationAttribute(Type entryPointType)