code: public List<Assignment> enumerateAllModels(final Variable[] variables, final ModelEnumerationHandler handler) {
          return this.enumerateAllModels(Arrays.asList(variables), handler);
      }
docs: Enumerates all models of the current formula wrt. a given set of variables and passes it to a model
  enumeration handler.  If the set is {@code null}, all literals are considered relevant.
  @param variables the set of variables
  @param handler   the model enumeration handler
  @return the list of models