feat: add option to add description to tags (#2939)

Author: same-id

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

@@ -21,6 +21,8 @@ tags:
 - name: "camelCaseServiceName"
 - name: "AnotherServiceWithNoBindings"
 - name: "SnakeEnumService"
+- name: "echo rpc"
+  description: "Echo Rpc description"
 schemes:
 - "http"
 - "https"

examples/internal/proto/examplepb/a_bit_of_everything.pb.go

@@ -185,6 +185,10 @@ option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_swagger) = {
       }
     }
   }
+  tags: {
+    name: "echo rpc"
+    description: "Echo Rpc description"
+  }
   extensions: {
     key: "x-grpc-gateway-foo";
     value {

examples/internal/proto/examplepb/a_bit_of_everything.proto

@@ -31,6 +31,10 @@
     },
     {
       "name": "SnakeEnumService"
+    },
+    {
+      "name": "echo rpc",
+      "description": "Echo Rpc description"
     }
   ],
   "schemes": [

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

@@ -1847,6 +1847,21 @@ func applyTemplate(p param) (*openapiSwaggerObject, error) {
 			s.extensions = exts
 		}
 
+		if spb.Tags != nil {
+			for _, v := range spb.Tags {
+				newTag := openapiTagObject{}
+				newTag.Name = v.Name
+				newTag.Description = v.Description
+				if v.ExternalDocs != nil {
+					newTag.ExternalDocs = &openapiExternalDocumentationObject{
+						Description: v.ExternalDocs.Description,
+						URL:         v.ExternalDocs.Url,
+					}
+				}
+				s.Tags = append(s.Tags, newTag)
+			}
+		}
+
 		// Additional fields on the OpenAPI v2 spec's "OpenAPI" object
 		// should be added here, once supported in the proto.
 	}