fix: error handling and vendor

vendor/github.com/go-openapi/spec/external_docs.go

@@ -0,0 +1,24 @@
+// Copyright 2015 go-swagger maintainers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package spec
+
+// ExternalDocumentation allows referencing an external resource for
+// extended documentation.
+//
+// For more information: http://goo.gl/8us55a#externalDocumentationObject
+type ExternalDocumentation struct {
+	Description string `json:"description,omitempty"`
+	URL         string `json:"url,omitempty"`
+}