If a mortgagee of a recorded mortgage or a trustee of a recorded deed of trust or other purchaser of an apartment obtains possession of the apartment as a result of foreclosure of the mortgage or deed of trust, the possessor, and successors and assigns of the possessor are not liable for the share of the common expenses or assessments by the association of apartment owners chargeable to the apartment that became due before possession. This unpaid share of common expenses or assessments is a common expense collectable from all of the apartment owners including the possessor and successors and assigns of the possessor.