For NuGet 2.0, we made client and server changes to improve tab completion. The client will try to get tab completion data (package IDs and package versions) via an endpoint that returns minimal JSON instead of using OData as it does today.
If the current package source doesn't have the new endpoints, the client will fall back to using the old tab completion calls. So, even if your custom feeds don't have the new API, the client's tab completion will continue to work.
If the client is on the `All` aggregate package source, and any one of the individual package sources doesn't have the new endpoints, it will fall back for the **all** of them. That's why we'd love to see folks hosting custom package servers implement the
Documentation for the endpoint is here: https://github.com/NuGet/NuGetGallery/wiki/Tab-Completion-API-Endpoints