Change from 'Swagger: ' to 'OpenAPI: ' prefix.

examples/examplepb/echo_service.proto

@@ -6,7 +6,7 @@ option go_package = "examplepb";
 // Echo Service API consists of a single service which returns
 // a message.
 //
-// Swagger: {
+// OpenAPI: {
 //   "info": {
 //     "title": "Echo Service",
 //     "version": "1.0",
@@ -28,7 +28,7 @@ import "google/api/annotations.proto";
 
 // SimpleMessage represents a simple message sent to the Echo service.
 //
-// Swagger: {
+// OpenAPI: {
 //   "externalDocs": {
 //     "url": "http://github.com/gengo/grpc-gateway",
 //     "description": "Find out more about EchoService"
@@ -46,7 +46,7 @@ service EchoService {
 	// The message posted as the id parameter will also be
 	// returned.
 	//
-	// Swagger: {
+	// OpenAPI: {
 	//   "externalDocs": {
 	//     "url": "http://github.com/gengo/grpc-gateway",
 	//     "description": "Find out more about EchoService"

protoc-gen-swagger/genswagger/template.go

@@ -552,7 +552,7 @@ func applyTemplate(p param) (string, error) {
 //
 // To apply additional Swagger properties, one can pass valid JSON
 // in the last paragraph of the comment. The last paragraph needs to start
-// with the string 'Swagger: '. This JSON gets parsed and applied to
+// with the string 'OpenAPI: '. This JSON gets parsed and applied to
 // the passed swaggerObject directly. This lets developers easily apply
 // custom properties such as contact details, API base path, et al.
 func updateSwaggerDataFromComments(swaggerObject interface{}, comment string) error {
@@ -582,8 +582,8 @@ func updateSwaggerDataFromComments(swaggerObject interface{}, comment string) er
 	// TODO(ivucica): apply extras /after/ applying summary
 	// and description.
 	paragraphs := strings.Split(comment, "\n\n")
-	if len(paragraphs) > 0 && strings.HasPrefix(strings.TrimLeft(paragraphs[len(paragraphs)-1], " "), "Swagger: ") {
-		if err := json.Unmarshal([]byte(strings.TrimLeft(paragraphs[len(paragraphs)-1], " "))[len("Swagger: "):], swaggerObject); err != nil {
+	if len(paragraphs) > 0 && strings.HasPrefix(strings.TrimLeft(paragraphs[len(paragraphs)-1], " "), "OpenAPI: ") {
+		if err := json.Unmarshal([]byte(strings.TrimLeft(paragraphs[len(paragraphs)-1], " "))[len("OpenAPI: "):], swaggerObject); err != nil {
 			return fmt.Errorf("error: %s, parsing: %s", err.Error(), paragraphs[len(paragraphs)-1])
 		}
 		paragraphs = paragraphs[:len(paragraphs)-1]