add extensions for Tag object

examples/internal/clients/abe/api/swagger.yaml

@@ -23,6 +23,7 @@ tags:
 - name: "SnakeEnumService"
 - name: "echo rpc"
   description: "Echo Rpc description"
+  x-traitTag: true
 schemes:
 - "http"
 - "https"

examples/internal/clients/unannotatedecho/api/swagger.yaml

@@ -22,6 +22,11 @@ tags:
   externalDocs:
     description: "Find out more about UnannotatedEchoService"
     url: "https://github.com/grpc-ecosystem/grpc-gateway"
+- name: "Echo"
+  description: "Echo description"
+- name: "Internal"
+  description: "Internal description"
+  x-traitTag: true
 schemes:
 - "http"
 - "https"

examples/internal/proto/examplepb/a_bit_of_everything.proto

@@ -188,6 +188,12 @@ option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_swagger) = {
   tags: {
     name: "echo rpc"
     description: "Echo Rpc description"
+    extensions: {
+      key: "x-traitTag";
+      value {
+        bool_value: true;
+      }
+    }
   }
   extensions: {
     key: "x-grpc-gateway-foo";

examples/internal/proto/examplepb/a_bit_of_everything.swagger.json

@@ -34,7 +34,8 @@
     },
     {
       "name": "echo rpc",
-      "description": "Echo Rpc description"
+      "description": "Echo Rpc description",
+      "x-traitTag": true
     }
   ],
   "schemes": [

examples/internal/proto/examplepb/unannotated_echo_service.swagger.json

@@ -23,6 +23,15 @@
         "description": "Find out more about UnannotatedEchoService",
         "url": "https://github.com/grpc-ecosystem/grpc-gateway"
       }
+    },
+    {
+      "name": "Echo",
+      "description": "Echo description"
+    },
+    {
+      "name": "Internal",
+      "description": "Internal description",
+      "x-traitTag": true
     }
   ],
   "schemes": [

examples/internal/proto/examplepb/unannotated_echo_service.swagger.yaml

@@ -15,6 +15,13 @@ openapiOptions:
           version: "1.0"
           extensions:
             x-something-something: yadda
+        tags:
+          - name: Echo
+            description: Echo description
+          - name: Internal
+            description: Internal description
+            extensions:
+              x-traitTag: true
         schemes:
           - HTTP
           - HTTPS

protoc-gen-openapiv2/internal/genopenapi/generator.go

@@ -218,6 +218,23 @@ func (so openapiParameterObject) MarshalYAML() (interface{}, error) {
 	}, nil
 }
 
+func (so openapiTagObject) MarshalJSON() ([]byte, error) {
+	type alias openapiTagObject
+	return extensionMarshalJSON(alias(so), so.extensions)
+}
+
+func (so openapiTagObject) MarshalYAML() (interface{}, error) {
+	type Alias openapiTagObject
+
+	return struct {
+		Extension map[string]interface{} `yaml:",inline"`
+		Alias     `yaml:",inline"`
+	}{
+		Extension: extensionsToMap(so.extensions),
+		Alias:     Alias(so),
+	}, nil
+}
+
 func extensionMarshalJSON(so interface{}, extensions []extension) ([]byte, error) {
 	// To append arbitrary keys to the struct we'll render into json,
 	// we're creating another struct that embeds the original one, and

protoc-gen-openapiv2/internal/genopenapi/template.go

@@ -1858,6 +1858,13 @@ func applyTemplate(p param) (*openapiSwaggerObject, error) {
 						URL:         v.ExternalDocs.Url,
 					}
 				}
+				if v.Extensions != nil {
+					exts, err := processExtensions(v.Extensions)
+					if err != nil {
+						return nil, err
+					}
+					newTag.extensions = exts
+				}
 				s.Tags = append(s.Tags, newTag)
 			}
 		}

protoc-gen-openapiv2/internal/genopenapi/template_test.go

@@ -1834,6 +1834,15 @@ func TestApplyTemplateExtensions(t *testing.T) {
 				},
 			},
 		},
+		Tags: []*openapi_options.Tag{
+			{
+				Name:        "test tag",
+				Description: "test tag description",
+				Extensions: map[string]*structpb.Value{
+					"x-traitTag": {Kind: &structpb.Value_BoolValue{BoolValue: true}},
+				},
+			},
+		},
 	}
 	openapiOperation := openapi_options.Operation{
 		Responses: map[string]*openapi_options.Response{
@@ -1936,6 +1945,16 @@ func TestApplyTemplateExtensions(t *testing.T) {
 		}, response.extensions, "response.Extensions"; !reflect.DeepEqual(is, want) {
 			t.Errorf("applyTemplate(%#v).%s = %s want to be %s", file, name, is, want)
 		}
+
+		var tag openapiTagObject
+		for _, v := range result.Tags {
+			tag = v
+		}
+		if want, is, name := []extension{
+			{key: "x-traitTag", value: json.RawMessage("true")},
+		}, tag.extensions, "Tags[0].Extensions"; !reflect.DeepEqual(is, want) {
+			t.Errorf("applyTemplate(%#v).%s = %s want to be %s", file, name, is, want)
+		}
 	}
 	t.Run("verify template options set via proto options", func(t *testing.T) {
 		file := newFile()

protoc-gen-openapiv2/internal/genopenapi/types.go

@@ -31,6 +31,8 @@ type openapiTagObject struct {
 	Name         string                              `json:"name" yaml:"name"`
 	Description  string                              `json:"description,omitempty" yaml:"description,omitempty"`
 	ExternalDocs *openapiExternalDocumentationObject `json:"externalDocs,omitempty" yaml:"externalDocs,omitempty"`
+
+	extensions []extension `json:"-" yaml:"-"`
 }
 
 // http://swagger.io/specification/#contactObject