private static IEnumerable <ILibraryOperationResult> GetDuplicateLibrariesErrors(IEnumerable <ILibraryInstallationState> libraries) { var errors = new List <ILibraryOperationResult>(); HashSet <string> duplicateLibraries = GetDuplicateLibraries(libraries); if (duplicateLibraries.Count > 0) { foreach (string libraryName in duplicateLibraries) { errors.Add(LibraryOperationResult.FromError(PredefinedErrors.DuplicateLibrariesInManifest(libraryName))); } } return(errors); }