code: public DBEngineVersion withValidUpgradeTarget(UpgradeTarget... validUpgradeTarget) {
          if (this.validUpgradeTarget == null) {
              setValidUpgradeTarget(new java.util.ArrayList<UpgradeTarget>(validUpgradeTarget.length));
          }
          for (UpgradeTarget ele : validUpgradeTarget) {
              this.validUpgradeTarget.add(ele);
          }
          return this;
      }
docs: <p>
  A list of engine versions that this database engine version can be upgraded to.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setValidUpgradeTarget(java.util.Collection)} or {@link #withValidUpgradeTarget(java.util.Collection)} if
  you want to override the existing values.
  </p>
  
  @param validUpgradeTarget
  A list of engine versions that this database engine version can be upgraded to.
  @return Returns a reference to this object so that method calls can be chained together.