Knowing that 行く is punctual, stative, and a motion verb, I also know that,
日本に行っている means "I/he/she have gone to Japan (and am still there)" rather than "I am currently going to Japan."
I also feel that 行っている can be used in the sense of habitual action, so that
大学に行っている can mean either "I'm at the college" or "I go to college" depending on the context.
That being said, can I also use 行っている in the sense of a habitual action in conjunction with 間（に)?
大学に行っている間、もっと勉強すればよかった。- I wish I had studied more when I was going to college.
大学に行っている間に高校の彼女と別れました。- While I was in college, I broke up with my girlfriend from high school.
大学に行っている間、雨が降りました。- It was raining while I was at school.
大学に行っている間に宿題をしました。- I did my homework while I was at school.