Fix blackbox test

Signed-off-by: Eugenio Collado <[email protected]>

test/blackbox/common/DDSBlackboxTestsListeners.cpp

@@ -2982,6 +2982,9 @@ TEST(DDSStatus, sample_rejected_waitset)
             .disable_builtin_transport()
             .add_user_transport_to_pparams(testTransport)
             .disable_heartbeat_piggyback(true)
+            .asynchronously(eprosima::fastdds::dds::PublishModeQosPolicyKind::ASYNCHRONOUS_PUBLISH_MODE)
+            .add_flow_controller_descriptor_to_pparams( // Be sure are sent in separate submessage each DATA.
+        eprosima::fastdds::rtps::FlowControllerSchedulerPolicy::FIFO, 300, 300) // Be sure the first message is processed before sending the second.
             .init();
 
     reader.history_kind(eprosima::fastdds::dds::KEEP_ALL_HISTORY_QOS)