public async Task <LSP.SignatureHelp?> HandleRequestAsync(LSP.TextDocumentPositionParams request, RequestContext context, CancellationToken cancellationToken)
        {
            var document = context.Document;

            if (document == null)
            {
                return(null);
            }

            var position = await document.GetPositionFromLinePositionAsync(ProtocolConversions.PositionToLinePosition(request.Position), cancellationToken).ConfigureAwait(false);

            var providers   = _allProviders.Where(p => p.Metadata.Language == document.Project.Language);
            var triggerInfo = new SignatureHelpTriggerInfo(SignatureHelpTriggerReason.InvokeSignatureHelpCommand);
            var options     = _globalOptions.GetSignatureHelpOptions(document.Project.Language);

            foreach (var provider in providers)
            {
                var items = await provider.Value.GetItemsAsync(document, position, triggerInfo, options, cancellationToken).ConfigureAwait(false);

                if (items != null)
                {
                    var sigInfos = new ArrayBuilder <LSP.SignatureInformation>();

                    foreach (var item in items.Items)
                    {
                        LSP.SignatureInformation sigInfo;
                        if (context.ClientCapabilities?.HasVisualStudioLspCapability() == true)
                        {
                            sigInfo = new LSP.VSInternalSignatureInformation
                            {
                                ColorizedLabel = GetSignatureClassifiedText(item)
                            };
                        }
                        else
                        {
                            sigInfo = new LSP.SignatureInformation();
                        }

                        sigInfo.Label         = GetSignatureText(item);
                        sigInfo.Documentation = new LSP.MarkupContent {
                            Kind = LSP.MarkupKind.PlainText, Value = item.DocumentationFactory(cancellationToken).GetFullText()
                        };
                        sigInfo.Parameters = item.Parameters.Select(p => new LSP.ParameterInformation
                        {
                            Label         = p.Name,
                            Documentation = new LSP.MarkupContent {
                                Kind = LSP.MarkupKind.PlainText, Value = p.DocumentationFactory(cancellationToken).GetFullText()
                            }
                        }).ToArray();
                        sigInfos.Add(sigInfo);
                    }

                    var sigHelp = new LSP.SignatureHelp
                    {
                        ActiveSignature = GetActiveSignature(items),
                        ActiveParameter = items.ArgumentIndex,
                        Signatures      = sigInfos.ToArrayAndFree()
                    };

                    return(sigHelp);
                }
            }

            return(null);
        }