When attempting to add a NuGet reference to Sitecore.Commerce.Engine.Orders, version 2.1.5, I get the following error:
NU1603: Sitecore.Commerce.Plugin.Availability 2.1.3 depends on Sitecore.Commerce.Plugin.Catalog (>= 2.1.9) but Sitecore.Commerce.Plugin.Catalog 2.1.9 was not found. An approximate best match of Sitecore.Commerce.Plugin.Catalog 2.1.10 was resolved.
Package restore failed. Rolling back package changes for '<MyProjectName>'.