  The stationary states of nonlinear Schr{\"o}dinger equation on a ring with a
defect is numerically analyzed. Unconventional connection conditions are
imposed on the point defect, and it is shown that the system displays energy
level crossings and level shifts and associated quantum holonomies in the space
of system parameters, just as in the corresponding linear system. In the space
of nonlinearity parameter, on the other hand, the degeneracy occurs on a line,
excluding the possibility of any anholonomies. In contrast to the linear case,
existence of exotic phenomena such as disappearance of energy level and
foam-like structure are confirmed.
