When extending DateTime? or Guid? property for entity ，can not save success.
（Guid? Property）stack trace:
System.InvalidCastException: Object must implement IConvertible.
at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)
at Volo.Abp.EntityFrameworkCore.AbpDbContext1.HandleExtraPropertiesOnSave(EntityEntry entry) at Volo.Abp.EntityFrameworkCore.AbpDbContext1.ApplyAbpConcepts(EntityEntry entry, EntityChangeReport changeReport)
at Volo.Abp.EntityFrameworkCore.AbpDbContext1.ApplyAbpConcepts() at Volo.Abp.EntityFrameworkCore.AbpDbContext1.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Volo.Abp.Domain.Repositories.EntityFrameworkCore.EfCoreRepository`2.UpdateAsync(TEntity entity, Boolean autoSave, CancellationToken cancellationToken)

（DateTime? Property）stack trace:
System.InvalidCastException: Invalid cast from 'System.DateTime' to 'System.Nullable1[[System.DateTime, System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]]'. at System.Convert.DefaultToType(IConvertible value, Type targetType, IFormatProvider provider) at System.DateTime.System.IConvertible.ToType(Type type, IFormatProvider provider) at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider) at Volo.Abp.EntityFrameworkCore.AbpDbContext1.HandleExtraPropertiesOnSave(EntityEntry entry)
at Volo.Abp.EntityFrameworkCore.AbpDbContext1.ApplyAbpConcepts(EntityEntry entry, EntityChangeReport changeReport) at Volo.Abp.EntityFrameworkCore.AbpDbContext1.ApplyAbpConcepts()
at Volo.Abp.EntityFrameworkCore.AbpDbContext1.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken) at Volo.Abp.Domain.Repositories.EntityFrameworkCore.EfCoreRepository2.UpdateAsync(TEntity entity, Boolean autoSave, CancellationToken cancellationToken)

Reproduce steps：
Setp1.Add extra properties to AppUser

public virtual Guid? NullableGuidProperty { get; set; }

public virtual DateTime? NullableDateTimeProperty { get; set; }

Setp2. Config in EfCoreEntityExtensionMappings file

ObjectExtensionManager.Instance .MapEfCoreProperty<IdentityUser, Guid?>("NullableGuidProperty");

ObjectExtensionManager.Instance.MapEfCoreProperty<IdentityUser, DateTime?>("NullableDateTimeProperty");

Setp3.Update User

var user = await UserManager.GetByIdAsync(id);
user.SetProperty("NullableDateTimeProperty", DateTime.Now);
user.SetProperty("NullableGuidProperty", GuidGenerator.Create());
await _userRepository.UpdateAsync(user, true);