Backing out 'swagger extras' JSON code, per [request][1].

[1]: grpc-ecosystem#134 (comment)

examples/examplepb/echo_service.proto

@@ -5,39 +5,11 @@ option go_package = "examplepb";
 //
 // Echo Service API consists of a single service which returns
 // a message.
-//
-// <!-- swagger extras start
-// {
-//   "info": {
-//     "title": "Echo Service",
-//     "version": "1.0",
-//     "contact": {
-//       "name": "gRPC-Gateway project",
-//       "url": "https://github.com/gengo/grpc-gateway",
-//       "email": "none@example.com"
-//     }
-//   },
-//   "host": "localhost",
-//   "externalDocs": {
-//     "url": "https://github.com/gengo/grpc-gateway",
-//     "description": "More about gRPC-Gateway"
-//   }
-// }
-// swagger extras end -->
 package gengo.grpc.gateway.examples.examplepb;
 
 import "google/api/annotations.proto";
 
 // SimpleMessage represents a simple message sent to the Echo service.
-//
-// <!-- swagger extras start
-// {
-//   "externalDocs": {
-//     "url": "http://github.com/gengo/grpc-gateway",
-//     "description": "Find out more about EchoService"
-//   }
-// }
-// swagger extras end -->
 message SimpleMessage {
 	// Id represents the message identifier.
 	string id = 1;
@@ -49,15 +21,6 @@ service EchoService {
 	//
 	// The message posted as the id parameter will also be
 	// returned.
-	//
-	// <!-- swagger extras start
-	// {
-	//   "externalDocs": {
-	//     "url": "http://github.com/gengo/grpc-gateway",
-	//     "description": "Find out more about EchoService"
-	//   }
-	// }
-	// swagger extras end -->
 	rpc Echo(SimpleMessage) returns (SimpleMessage) {
 		option (google.api.http) = {
 			post: "/v1/example/echo/{id}"

examples/examplepb/echo_service.swagger.json

@@ -3,14 +3,8 @@
   "info": {
     "title": "Echo Service",
     "description": "Echo Service API consists of a single service which returns\na message.",
-    "version": "1.0",
-    "contact": {
-      "name": "gRPC-Gateway project",
-      "url": "https://github.com/gengo/grpc-gateway",
-      "email": "none@example.com"
-    }
+    "version": "version not set"
   },
-  "host": "localhost",
   "schemes": [
     "http",
     "https"
@@ -46,11 +40,7 @@
         ],
         "tags": [
           "EchoService"
-        ],
-        "externalDocs": {
-          "description": "Find out more about EchoService",
-          "url": "http://github.com/gengo/grpc-gateway"
-        }
+        ]
       }
     },
     "/v1/example/echo_body": {

protoc-gen-swagger/genswagger/template.go

@@ -13,8 +13,6 @@ import (
 	pbdescriptor "github.com/golang/protobuf/protoc-gen-go/descriptor"
 )
 
-var swaggerExtrasRegexp = regexp.MustCompile(`(?s)^(.*[^\s])[\s]*<!-- swagger extras start(.*)swagger extras end -->[\s]*(.*)$`)
-
 // findServicesMessagesAndEnumerations discovers all messages and enums defined in the RPC methods of the service.
 func findServicesMessagesAndEnumerations(s []*descriptor.Service, reg *descriptor.Registry, m messageMap, e enumMap) {
 	for _, svc := range s {
@@ -541,55 +539,20 @@ func applyTemplate(p param) (string, error) {
 // updateSwaggerDataFromComments updates a Swagger object based on a comment
 // from the proto file.
 //
-// As a first step, a section matching:
-//
-//     <!-- swagger extras start.*swagger extras end-->
-//
-// where .* contains valid JSON will be stored for later processing, and then
-// removed from the passed string.
-// (Implementation note: Currently, the JSON gets immediately applied and
-// thus cannot override summary and description.)
-//
 // First paragraph of a comment is used for summary. Remaining paragraphs of a
 // comment are used for description. If 'Summary' field is not present on the
 // passed swaggerObject, the summary and description are joined by \n\n.
 //
 // If there is a field named 'Info', its 'Summary' and 'Description' fields
-// will be updated instead. (JSON always gets applied directly to the passed
-// object.)
+// will be updated instead.
 //
 // If there is no 'Summary', the same behavior will be attempted on 'Title',
 // but only if the last character is not a period.
-//
-// To apply additional Swagger properties, one can pass valid JSON as described
-// before. This JSON gets parsed and applied to the passed swaggerObject
-// directly. This lets users easily apply custom properties such as contact
-// details, API base path, et al.
 func updateSwaggerDataFromComments(swaggerObject interface{}, comment string) error {
 	if len(comment) == 0 {
 		return nil
 	}
 
-	// Find a section containing additional Swagger metadata.
-	matches := swaggerExtrasRegexp.FindStringSubmatch(comment)
-
-	if len(matches) > 0 {
-		// If found, before further processing, replace the
-		// comment with a version that does not contain the
-		// extras.
-		comment = matches[1]
-		if len(matches[3]) > 0 {
-			comment += "\n\n" + matches[3]
-		}
-
-		// Parse the JSON and apply it.
-		// TODO(ivucica): apply extras /after/ applying summary
-		// and description.
-		if err := json.Unmarshal([]byte(matches[2]), swaggerObject); err != nil {
-			return fmt.Errorf("error: %s, parsing: %s", err.Error(), matches[2])
-		}
-	}
-
 	// Figure out what to apply changes to.
 	swaggerObjectValue := reflect.ValueOf(swaggerObject)
 	infoObjectValue := swaggerObjectValue.Elem().FieldByName("Info")