  The Kerr metric models the final classical black hole state after
gravitational collapse of matter and radiation. Any stationary metric which is
close to the Kerr metric has been proven to be diffeomorphic to it. Now, finite
supertranslation diffeomorphisms are symmetries which map solutions to
inequivalent solutions as such diffeomorphisms generate conserved superrotation
charges. The final state of gravitational collapse is therefore parameterized
by its mass, angular momentum and supertranslation field, signaled by its
conserved superrotation charges.
  In this paper, we first derive the angle-dependent energy conservation law
relating the asymptotic value of the supertranslation field of the final state
to the details of the collapse and subsequent evolution of the system. We then
generate the static solution with an asymptotic supertranslation field and we
study some of its properties. Up to a caveat, the deviation from the
Schwarzschild metric could therefore be predicted on a case-by-case basis from
accurate modeling of the angular dependence of the ingoing and outgoing energy
fluxes leading to the final state.
