code: public void addSoftClause(int weight, final LNGIntVector lits) {
      final LNGIntVector rVars = new LNGIntVector();
      this.softClauses.push(new MSSoftClause(lits, weight, LIT_UNDEF, rVars));
      this.nbSoft++;
    }
docs: Adds a new soft clause to the soft clause database.
  @param weight the weight of the soft clause
  @param lits   the literals of the soft clause