VSMEF017 Invalid [MetadataView] usage

VSMEF017 reports an error when MetadataViewAttribute is applied to an interface that the VS MEF source generator cannot handle.

Valid [MetadataView] targets

[MetadataView] should be applied only to metadata-view interfaces that:

• are declared partial
• are nested only inside partial containing types
• contain only get-only, non-indexer properties

Example

This triggers VSMEF017 because the interface is not partial:

using Microsoft.VisualStudio.Composition;

[MetadataView]
public interface IMyMetadata
{
    string Name { get; }
}

Make the interface (and any containing types) partial, and keep the interface to simple property-bag members.