Admiral Brickington

Just to add my two cents, if I may - when we are talking Imperial Army, then yes, that is the rank of a general, although they usually have only one code cylinder as shown on the pictures you provided, whereas the figure from the Advent calendar has two of them. However, as far as I know, within the Imperial Navy, four red squares atop four blue, along with two code cylinders, signify the rank of commodore. In any case, I'm glad we're finally getting something different than the usual three-red-atop-three-blue-squares officers :)

This is actually quite funny. LEGO named this minifigure 'First Order General', but the only item signifying the rank of a general is the black cap. The uniform is of a colonel/major, although the colour is wrong (it should be teal or turquoise), and the armband is of an admiral (because of the red stripes). So only the cap and maybe the overall black colour of his uniform are correct for a general (however, black coloured uniforms are also worn by sergeants/squad leaders...). Therefore, it may well be that LEGO just did not get this one right, or this minifigure may in fact be what a First Order Admiral looks like, or funnily enough, this minifigure is the "ultimate First Order Officer", or something along those lines. :) All this (un)intentional confusion makes this minifigure interesting, even intriguing for me, and I will definitely be getting one or two, if not for the whole minifigure, then at least for the individual parts.