Make explicit the need to keep alive the flow controller descriptor name (#806)

* Refs #21054: Make explicit the need for keeping alive participants flow controller descriptor name

Signed-off-by: Mario Dominguez <mariodominguez@eprosima.com>

* Refs #21054: Missing ;

Signed-off-by: Mario Dominguez <mariodominguez@eprosima.com>

* Refs #21054: Apply suggestions

---------

Signed-off-by: Mario Dominguez <mariodominguez@eprosima.com>
Co-authored-by: Eduardo Ponz Segrelles <eduardoponz@eprosima.com>

Author: Mario-DL

code/DDSCodeTester.cpp

@@ -4094,8 +4094,11 @@ void dds_qos_examples()
         //The PublishModeQosPolicy is default constructed with kind = SYNCHRONOUS
         //Change the kind to ASYNCHRONOUS
         publish_mode.kind = ASYNCHRONOUS_PUBLISH_MODE;
+
         // Optionally, select the flow controller name
-        publish_mode.flow_controller_name = "example_flow_controller";
+        // Important: the flow_controller_name must be kept alive during the Participant's lifetime.
+        static std::string flow_controller_name{"example_flow_controller"};
+        publish_mode.flow_controller_name = flow_controller_name.c_str();
         //!--
     }
 
@@ -5409,6 +5412,7 @@ void dds_usecase_examples()
     {
         //CONF-QOS-FLOWCONTROLLER
         // Limit to 300kb per second.
+        // Important: the flow_controller_name must be kept alive during the Participant's lifetime.
         static const char* flow_controller_name = "example_flow_controller";
         auto flow_control_300k_per_sec = std::make_shared<eprosima::fastdds::rtps::FlowControllerDescriptor>();
         flow_control_300k_per_sec->name = flow_controller_name;