Impossible to find the energy stored in an inductor without resistance and given a constant DC current source?
OK, so that's a trick question. Or a trick circuit, take your pick.

Let's start at the beginning. At some point the current through the circuit will be zero amps, and then the current source will be activated.

During turn-on, when the current source is connected or otherwise activated, the existence of a non-zero di/dt will produce non-zero voltages in all inductors which actually conduct current. Due to the short circuit across L3, there can be no voltage produced in L3 to L9, and consequently no current introduced into L3 to L9. With no instantaneous current at any time, the integral of the current in L3 to L9 must also be zero. So, at steady-state, only L1 and L2 have current flowing through them, and the current must be identically 10 amps in each.

From this you can calculate the total energy stored in all inductors.