EmptyCollectionIfNull no longer initializes empty collections in reccords for nullable source

[moikot]

I believe commit 1117602 introduced in v10.0.7-pre1 a regression in Mapster.

Previously, when using the EmptyCollectionIfNull destination transform, a null collection in the source would correctly map to an empty collection in the destination. After this change, that behavior no longer works.

class FooDto
{
    public string[] Strings { get; set; }
}

record Foo(List<string> Strings);

// Configure
TypeAdapterConfig.GlobalSettings.Default
    .AddDestinationTransform(DestinationTransform.EmptyCollectionIfNull);

// Arrange
var fooDto = new FooDto();

// Act
var foo = fooDto.Adapt<Foo>();

// Assert
foo.Strings.ShouldNotBeNull();

Expected Behavior

foo.Strings should be initialized as an empty array (string[0]), not null.

Actual Behavior

foo.Strings is null.

Impact

This regression makes migration from AutoMapper significantly more difficult, as AutoMapper applies this behavior by default (null collections are mapped to empty ones).

[DocSvartz]

Hi, @moikot based on origin tests, this settings was intended to Properties or members of destination Type that are of collection.
So, in terms of constructor parameters, it was undocumented behavior.

I have a couple of ideas on how to get this back.