Automapper ignore execution plan

Automapper.cs

static void Main(string[] args)
{
	Mapper.Initialize(cfg =>
	{

		cfg.AddProfiles(new Profile[] { new CaseProfile()});
	});
	var configuration = new MapperConfiguration(cfg => cfg.CreateMap<CaseView, Case>());
	var executionPlan = configuration.BuildExecutionPlan(typeof(CaseView), typeof(Case));
	// Compare execution plans
	executionPlan.ToReadableString().Dump();
	
	
// I can't reproduce the error I'm seeing with EF proxies yet
//	var caseView = new CaseView(){
//		User = new UserView{
//			UserID = 5
//		},
//		UserID = 5
//	};
//	var existingCase = new Case(){
//		User = new UserChild(){ UserID = 1 }
//	};
//	var result = Mapper.Map<CaseView, Case>(caseView, existingCase);
//	if (result.User.UserID == 5) {
//		throw new Exception("Should not have mapped");
//	}
}

public class UserView {
	public int UserID {get; set;}
}
public class User {
	public int UserID { get; set; }
}

public class UserChild : User {
	
}

public class Case
{
// 1: Works
//	[IgnoreMap]
//
	public virtual User User {get; set;}
	public int? UserID {get; set;}
}

public class CaseView
{
	public UserView User {get; set;}
	public int? UserID {get; set;}
}

public class CaseProfile : Profile {
	public CaseProfile()
	{
		CreateMap<CaseView, Case>()
// 2 doesn't work
//			.ForMember(x => x.User, opts => opts.Ignore())
// 3 doesn't work
//			.ForMember(x => x.User, opts => opts.MapFrom(src => (User)null))
			.ForMember(x => x.UserID, opts => opts.MapFrom (src => src.User.UserID));
		CreateMap<UserView, User>();
	}
	
}

Execution plans:
Default (no ignores)

(src, dest, ctxt) =>
{
    UserQuery.Case typeMapDestination;
    return (src == null)
        ? null
        : {
            typeMapDestination = dest ?? new UserQuery.Case();
            try
            {
                var resolvedValue = ((src == null) || false) ? null : src.User;
                var propertyValue =
                {
                    UserQuery.User typeMapDestination;
                    return (resolvedValue == null)
                        ? null
                        : {
                            ctxt.ValidateMap(TypeMap);
                            typeMapDestination = ((dest == null) ? null : typeMapDestination.User) ?? new UserQuery.User();
                            try
                            {
                                var resolvedValue = ((resolvedValue == null) || false) ? default(int) : resolvedValue.UserID;
                                typeMapDestination.UserID = resolvedValue;
                            }
                            catch (Exception ex)
                            {
                                throw new AutoMapperMappingException(
                                    "Error mapping types.",
                                    ex,
                                    AutoMapper.TypePair,
                                    TypeMap,
                                    PropertyMap);

                                return default(int);
                            }

                            return typeMapDestination;
                        };
                };

                typeMapDestination.User = propertyValue;
            }
            catch (Exception ex)
            {
                throw new AutoMapperMappingException(
                    "Error mapping types.",
                    ex,
                    AutoMapper.TypePair,
                    TypeMap,
                    PropertyMap);

                return null;
            }
            try
            {
                var resolvedValue = ((src == null) || false) ? null : src.UserID;
                var propertyValue = (resolvedValue == null) ? null : (int?)resolvedValue.Value;
                typeMapDestination.UserID = propertyValue;
            }
            catch (Exception ex)
            {
                throw new AutoMapperMappingException(
                    "Error mapping types.",
                    ex,
                    AutoMapper.TypePair,
                    TypeMap,
                    PropertyMap);

                return null;
            }

            return typeMapDestination;
        };
}

1: Ignoremap attribute:

(src, dest, ctxt) =>
{
    UserQuery.Case typeMapDestination;
    return (src == null)
        ? null
        : {
            typeMapDestination = dest ?? new UserQuery.Case();
            try
            {
                var resolvedValue = ((src == null) || false) ? null : src.UserID;
                var propertyValue = (resolvedValue == null) ? null : (int?)resolvedValue.Value;
                typeMapDestination.UserID = propertyValue;
            }
            catch (Exception ex)
            {
                throw new AutoMapperMappingException(
                    "Error mapping types.",
                    ex,
                    AutoMapper.TypePair,
                    TypeMap,
                    PropertyMap);

                return null;
            }

            return typeMapDestination;
        };
}

2/3: Ignore fluent/Null value

(src, dest, ctxt) =>
{
    UserQuery.Case typeMapDestination;
    return (src == null)
        ? null
        : {
            typeMapDestination = dest ?? new UserQuery.Case();
            try
            {
                var resolvedValue = ((src == null) || false) ? null : src.User;
                var propertyValue =
                {
                    UserQuery.User typeMapDestination;
                    return (resolvedValue == null)
                        ? null
                        : {
                            ctxt.ValidateMap(TypeMap);
                            typeMapDestination = ((dest == null) ? null : typeMapDestination.User) ?? new UserQuery.User();
                            try
                            {
                                var resolvedValue = ((resolvedValue == null) || false) ? default(int) : resolvedValue.UserID;
                                typeMapDestination.UserID = resolvedValue;
                            }
                            catch (Exception ex)
                            {
                                throw new AutoMapperMappingException(
                                    "Error mapping types.",
                                    ex,
                                    AutoMapper.TypePair,
                                    TypeMap,
                                    PropertyMap);

                                return default(int);
                            }

                            return typeMapDestination;
                        };
                };

                typeMapDestination.User = propertyValue;
            }
            catch (Exception ex)
            {
                throw new AutoMapperMappingException(
                    "Error mapping types.",
                    ex,
                    AutoMapper.TypePair,
                    TypeMap,
                    PropertyMap);

                return null;
            }
            try
            {
                var resolvedValue = ((src == null) || false) ? null : src.UserID;
                var propertyValue = (resolvedValue == null) ? null : (int?)resolvedValue.Value;
                typeMapDestination.UserID = propertyValue;
            }
            catch (Exception ex)
            {
                throw new AutoMapperMappingException(
                    "Error mapping types.",
                    ex,
                    AutoMapper.TypePair,
                    TypeMap,
                    PropertyMap);

                return null;
            }

            return typeMapDestination;
        };
}