AttributeError:'VehicleOpticalFlow' object has no attribute 'integration_time_us' in ros2 message publishing

I’m running PX4 v1.15.4 and publishing optical flow data from a custom ROS 2 node using the px4_msgs/VehicleOpticalFlow message. When I run my node, I get this error:

" AttributeError: ‘VehicleOpticalFlow’ object has no attribute ‘integration_time_us’
I’m using PX4 v1.15.4."

need advice