Adding google.api.Http annotation to Google Long Running Operations

API methods.

google/longrunning/operations.proto

@@ -16,6 +16,7 @@ syntax = "proto3";
 
 package google.longrunning;
 
+import "google/api/annotations.proto";
 import "google/protobuf/any.proto";
 import "google/protobuf/empty.proto";
 import "google/rpc/status.proto";
@@ -39,12 +40,16 @@ service Operations {
   // Gets the latest state of a long-running operation.  Clients may use this
   // method to poll the operation result at intervals as recommended by the API
   // service.
-  rpc GetOperation(GetOperationRequest) returns (Operation);
+  rpc GetOperation(GetOperationRequest) returns (Operation) {
+    option (google.api.http) = { get: "/v1/{name=operations/**}" };
+  }
 
   // Lists operations that match the specified filter in the request. If the
   // server doesn't support this method, it returns
   // `google.rpc.Code.UNIMPLEMENTED`.
-  rpc ListOperations(ListOperationsRequest) returns (ListOperationsResponse);
+  rpc ListOperations(ListOperationsRequest) returns (ListOperationsResponse) {
+    option (google.api.http) = { get: "/v1/{name=operations}" };
+  }
 
   // Starts asynchronous cancellation on a long-running operation.  The server
   // makes a best effort to cancel the operation, but success is not
@@ -52,11 +57,15 @@ service Operations {
   // `google.rpc.Code.UNIMPLEMENTED`.  Clients may use
   // [Operations.GetOperation] or other methods to check whether the
   // cancellation succeeded or the operation completed despite cancellation.
-  rpc CancelOperation(CancelOperationRequest) returns (google.protobuf.Empty);
+  rpc CancelOperation(CancelOperationRequest) returns (google.protobuf.Empty) {
+    option (google.api.http) = { post: "/v1/{name=operations/**}:cancel" body: "*" };
+  }
 
   // Deletes a long-running operation.  It indicates the client is no longer
   // interested in the operation result. It does not cancel the operation.
-  rpc DeleteOperation(DeleteOperationRequest) returns (google.protobuf.Empty);
+  rpc DeleteOperation(DeleteOperationRequest) returns (google.protobuf.Empty) {
+    option (google.api.http) = { delete: "/v1/{name=operations/**}" };
+  }
 }
 
 // This resource represents a long-running operation that is the result of a