code: public static boolean isSubtype(ReferenceType t, ReferenceType possibleSupertype) throws ClassNotFoundException {
          return Global.getAnalysisCache().getDatabase(Subtypes2.class).isSubtype(t, possibleSupertype);
      }
docs: Determine if one reference type is a subtype of another.
  
  @param t
  a reference type
  @param possibleSupertype
  the possible supertype
  @return true if t is a subtype of possibleSupertype, false if not