move request initialization to the constructor

Signed-off-by: Daisuke Sato <[email protected]>

Author: daisukes

nav2_behavior_tree/include/nav2_behavior_tree/bt_service_node.hpp

@@ -45,6 +45,9 @@ class BtServiceNode : public BT::SyncActionNode
     getInput("service_name", service_name_);
     service_client_ = node_->create_client<ServiceT>(service_name_);
 
+    // Make a request for the service without parameter
+    request_ = std::make_shared<typename ServiceT::Request>();
+
     // Make sure the server is actually there before continuing
     RCLCPP_INFO(
       node_->get_logger(), "Waiting for \"%s\" service",
@@ -83,7 +86,6 @@ class BtServiceNode : public BT::SyncActionNode
   // The main override required by a BT service
   BT::NodeStatus tick() override
   {
-    request_ = std::make_shared<typename ServiceT::Request>();
     on_tick();
     auto future_result = service_client_->async_send_request(request_);
     return check_future(future_result);