code: public OrCondition optimize() {
          for (AndCondition each : andConditions) {
              if (each.getConditions().get(0) instanceof NullCondition) {
                  OrCondition result = new OrCondition();
                  result.add(new NullCondition());
                  return result;
              }
          }
          return this;
      }
docs: Optimize or condition.
  
  @return or condition