Merging object does not allow to set a property value to null

[MikeAlhayek]

Describe the bug

I created a custom part:

public class TestContentPart : ContentPart
{
    public int? Minutes { get; set; }
}

Using a driver I have set the Minutes value to a number like 10. Everything works as expected. However, if I want to set it back to null after it was set to 10 the value will not allow setting null. because of this setting

OrchardCore/src/OrchardCore/OrchardCore.Abstractions/Json/JOptions.cs

Line 23 in 3fe9612

DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,

Orchard Core version

main

To Reproduce

Steps to reproduce the behavior:
Using the following test

  [Fact]
  public void Apply_WhenCalledWithNullProperty_SetThePropertyToNull()
  {
      var contentItem = new ContentItem();

      contentItem.Apply(new TestContentPart()
      {
          Minutes = -15,
      });

      var instance = contentItem.As<TestContentPart>();

      Assert.NotNull(instance);
      Assert.Equal(-15, instance.Minutes);

      contentItem.Apply(new TestContentPart()
      {
          Minutes = null,
      });

      var minutes = (int?)contentItem.Content.TestContentPart.Minutes;

      Assert.Null(minutes);
  }

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