docs: public DescribeRdsDbInstancesResult withRdsDbInstances(RdsDbInstance... rdsDbInstances) {
          if (this.rdsDbInstances == null) {
              setRdsDbInstances(new com.amazonaws.internal.SdkInternalList<RdsDbInstance>(rdsDbInstances.length));
          }
          for (RdsDbInstance ele : rdsDbInstances) {
              this.rdsDbInstances.add(ele);
          }
          return this;
      }