///<summary>A comma-separated list of fields for `fielddata` and `suggest` index metric (supports wildcards)</summary>
internal static IndicesStatsRequestParameters _CompletionFields <T>(this IndicesStatsRequestParameters qs, IEnumerable <Expression <Func <T, object> > > completion_fields) where T : class =>
qs.AddQueryString("completion_fields", completion_fields.Select(e => (Field)e));
