Communication Class Interface (0)    --- parent interface
    Union Function Descriptor (0)

    Communication Class Interface (1)    --- UART 1
      Union Function Descriptor (1)
      Data Class Interface (1)

    Communication Class Interface (2)    --- UART 2
      Union Function Descriptor (2)
      Data Class Interface (2)

    Communication Class Interface (3)    --- UART 3
      Union Function Descriptor (3)
      Data Class Interface (3)
    ...