public IDictionary <string, IReadOnlyCollection <string> > PrepareHeaders() { var headers = new Dictionary <string, IReadOnlyCollection <string> >(); _includes.ForEach(include => headers.Add($"{IncludePrefix}{include.Key}", include.Value)); headers.Add(IncludeAllPrefix, new[] { IncludeAll.ToString().ToLower() }); return(headers); }