macOS icon is inconsistent with other application icons

[js51]

Is your suggestion for improvement related to a problem? Please describe.

The current icon is inconsistent with Apple's human interface guidelines and with the vast majority of other applications developed for macOS. This means that JabRef looks quite strange on the dock, sitting next to other icons which conform to the guidelines:

You can also see that the icon brightness can be a problem, depending on the user's desktop wallpaper. The image above uses the current default wallpaper. This is related to issue #7771 and PR #7825.

Describe the solution you'd like
I'd like a new app icon to be used specifically for the macOS version of JabRef. I've included two quick proposals below but I think that anything that meets the guidelines linked above would be a big improvement.

The colours will of course depend on the outcome of #7825.

Additional context

[Siedlerchr]

Thanks a lot for your suggestion! I like the coloring idea. You haven't yet found time to decide on a new color scheme, so any suggestions are welcome.

[u7283157]

Hi, my team and I are planning to work on this issue and have it done by the end of October. Could we please be assigned this issue?

[Siedlerchr]

@u7283157 We are looking foward to your work. Please also have a look at the discussions here:
#7825
The idea was to have a multiple color shade icon like VSCode .
It would be cool to have screenshots how it would look like

[u7283157]

Hi, please find below some macOS icons I have designed. Please let me know what you think so far.

[renzoseverino]

Hi! I was trying to change my JabRef MacOS icon today and stumbled upon this. Are there any updates, please? The work so far looks great (specially the first row of the proposed icons). Thanks!!