PropertyLinkCollection loses all links if RemapPermanentLinkReferences is called

Description

The PropertyLinkCollection inherits from PropertyXhtmlString but doesn't populate the XhtmlString value if the value is set to a LinkCollection.

This has a few side effects, primarily that all links are removed if RemapPermanentLinkReferences is called.

Example unit test from PropertyLinkCollectionTest.cs.

[Fact]
public void RemapPermanentLinkReferences_WhenLinksAreSet_ShouldRemapLinks()
{
    var originalGuid = Guid.NewGuid();
    var remappedGuid = Guid.NewGuid();
 
    var property = new PropertyLinkCollection();
    property.Links = new LinkItemCollection { new LinkItem { Href = PermanentLinkUtility.GetPermanentLinkVirtualPath(originalGuid, ".txt"), UrlResolver = UrlResolver() } };
 
    var map = new Dictionary<Guid, Guid> { { originalGuid, remappedGuid } };
 
    property.RemapPermanentLinkReferences(map);
 
    var expected = PermanentLinkUtility.GetPermanentLinkVirtualPath(remappedGuid, ".txt");
 
    Assert.Equal(expected, property.Links[1].Href);
}

Breaking Changes

• PropertyLinkCollection no longer inherits PropertyXhtmlString. It is now a direct base class to PropertyLongString, which means that properties and methods inherited from PropertyXhtmlString are no longer available.