Composite descriptor generation using report_id

[HaoboGu]

Hello, I'm trying to create a composite descriptor which includes KeyboardReport/MouseReport/SystemControlReport etc.

The descriptor is defined as:

#[gen_hid_descriptor(
    (report_id = 0x01, collection = APPLICATION, usage_page = GENERIC_DESKTOP, usage = KEYBOARD) = {
        (usage_page = KEYBOARD, usage_min = 0xE0, usage_max = 0xE7) = {
            #[packed_bits 8] #[item_settings data,variable,absolute] modifier=input;
        };
        (usage_min = 0x00, usage_max = 0xFF) = {
            #[item_settings constant,variable,absolute] reserved=input;
        };
        (usage_page = LEDS, usage_min = 0x01, usage_max = 0x05) = {
            #[packed_bits 5] #[item_settings data,variable,absolute] leds=output;
        };
        (usage_page = KEYBOARD, usage_min = 0x00, usage_max = 0xDD) = {
            #[item_settings data,array,absolute] keycodes=input;
        };
    },
    (report_id = 0x02, collection = APPLICATION, usage_page = CONSUMER, usage = CONSUMER_CONTROL) = {
        (usage_page = CONSUMER, usage_min = 0x00, usage_max = 0x514) = {
            #[item_settings data,array,absolute,not_null] usage_id=input;
        };
    },
    (report_id = 0x03, collection = APPLICATION, usage_page = GENERIC_DESKTOP, usage = SYSTEM_CONTROL) = {
        (usage_min = 0x81, usage_max = 0xB7, logical_min = 1) = {
            #[item_settings data,array,absolute,not_null] usage_id=input;
        };
    }
)]
#[allow(dead_code)]
pub struct MyReport {
    pub modifier: u8,
    pub reserved: u8,
    pub leds: u8,
    pub keycodes: [u8; 6],
    pub usage_id: u16,
}

But I have problems about implementing usbd_hid::descriptor::AsInputReport for MyReport.

There is no documentation/example about how to implement AsInputReport trait for a custom report. @twitchyliquid64 any suggestions?