kazyx

public class Main {
    public Type GetTypeOfGenericArg(Type derivedClassType) {
        var typedMyInterfaceType = derivedClassType.GetInterface(typeof(MyInterface<>).FullName);

        // If derivedClassType is 'MyFoo', typedMyInterfaceType is typeof(MyInterface<Foo>)
        return typedMyInterfaceType.GetGenericArguments()[0];
    }
    
    public Type GetTypeOfGenericArgByPropertyName(Type derivedClassType) {
        var myParamPropertyInfo = derivedClassType.GetProperty(nameof(MyInterface.MyParameter));