ReturnData

use fuel_types::ContractId;
pub struct ReturnData {
    id: ContractId,
    data: Vec<u8>,
}

• A ReturnData receipt is generated when returning a reference type in a Sway contract; this includes all types except non-reference types.
• The data field will include the returned value as a hexadecimal.
• Read more about ReturnData in the Fuel protocol ABI spec