Merge pull request #1583 from yang-g/mock

remove redudant optional keyword in proto3

src/ruby/bin/math.proto

@@ -33,25 +33,25 @@ syntax = "proto3";
 package math;
 
 message DivArgs {
-  optional int64 dividend = 1;
+  int64 dividend = 1;
-  optional int64 divisor = 2;
+  int64 divisor = 2;
 }
 
 message DivReply {
-  optional int64 quotient = 1;
+  int64 quotient = 1;
-  optional int64 remainder = 2;
+  int64 remainder = 2;
 }
 
 message FibArgs {
-  optional int64 limit = 1;
+  int64 limit = 1;
 }
 
 message Num {
-  optional int64 num = 1;
+  int64 num = 1;
 }
 
 message FibReply {
-  optional int64 count = 1;
+  int64 count = 1;
 }
 
 service Math {