docs: public void setRdsDbInstances(java.util.Collection<RdsDbInstance> rdsDbInstances) {
          if (rdsDbInstances == null) {
              this.rdsDbInstances = null;
              return;
          }
  
          this.rdsDbInstances = new com.amazonaws.internal.SdkInternalList<RdsDbInstance>(rdsDbInstances);
      }