fix code style in pb_to_json.cpp

src/json2pb/pb_to_json.cpp

@@ -89,10 +89,10 @@ bool PbToJsonConverter::Convert(const google::protobuf::Message& message, Handle
                 _error = "Missing required field: " + field->full_name();
                 return false;
             }
-            
-            if(!_option.always_print_primitive_fields)
+            // Whether dumps default fields
+            if (!_option.always_print_primitive_fields) {
                 continue;
-               
+            }
         } else if (field->is_repeated()
                    && reflection->FieldSize(message, field) == 0
                    && !_option.jsonify_empty_array) {