Martha Finnemore in The Purpose of Intervention points out that prior to the Hague Conventions (1899, 1907) it was an accepted norm that countries could invade debtor nations to collect unpaid debts. The courts of arbitration set up by the international community largely ended this practice. The Venezuela Crisis of 1902 also elicited a great deal of international consternation precipitating the shift to accept this norm.

I dont think so, as it is not binding.

It depends on what you mean by binding. If you mean 'enforceable' then very little of the IHL is binding (broadly speaking), as strong countries can do what they want (as realists routinely remind us). But if you mean 'honored' or 'subscribed to' then that is a different matter. That states usually don't invade countries that default on their loans is an indication that states to some extent honor the function of arbitration, for whatever reason (it's cheaper, more effective, more humane...).