HID bidirectional communication on STM32 -- 2

I am looking for embedded guy who has worked with USB HID on STM32. My requirement is : The two STM32 devices are connected over USB line and communicating over HID class. Usually communication is uni-directional i.e device to host. But I am looking for bidirectional communication so that two STM32 devices can receive or transmit data with each other. Most probably you need to use custom HID in this case because generally communication is one sided only i.e from device to host. Like keyboard or mouse. But if communication is both ways host to Device, then custom HID will be used. You can connect two STM32 discovery boards with USB over OTG cable to make the connection and one will act as device and other as host. I need an API routine which I can call to transmit and receive data on any side. For testing you can print the data on UART which received from HID and similarly, send the data from UART to HID. Make sure to use CubeMX for code generation and Keil IDE/Cube IDE for programming.