Unfortunately I can’t find the answer 
With Java you can connect to the dashboard server, you can use socket communication to do this, and on the dashboard server send the command ‘robotmode’ to check status.
Roman, thank you for your answer. I thought maybe there is some API function to check it.
I looked through the API curious if there was anything but did not see any documentation for any. I can think of a few work arounds using Script writer, but the easiest way would be through the dashboard server.