/// <summary>
/// Create a new <see cref="Solution"/> instance with the corresponding <see cref="Project"/>s updated to include
/// the documents specified by <paramref name="documentInfos"/>.
/// </summary>
/// <returns>A new <see cref="Solution"/> with the documents added.</returns>
public Solution AddDocuments(ImmutableArray <DocumentInfo> documentInfos)
{
var newState = _state.AddDocuments(documentInfos);
if (newState == _state)
{
return(this);
}
return(new Solution(newState));
}