code: public ListReceiptRuleSetsResult withRuleSets(ReceiptRuleSetMetadata... ruleSets) {
          if (this.ruleSets == null) {
              setRuleSets(new com.amazonaws.internal.SdkInternalList<ReceiptRuleSetMetadata>(ruleSets.length));
          }
          for (ReceiptRuleSetMetadata ele : ruleSets) {
              this.ruleSets.add(ele);
          }
          return this;
      }
docs: <p>
  The metadata for the currently active receipt rule set. The metadata consists of the rule set name and the
  timestamp of when the rule set was created.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setRuleSets(java.util.Collection)} or {@link #withRuleSets(java.util.Collection)} if you want to override
  the existing values.
  </p>
  
  @param ruleSets
  The metadata for the currently active receipt rule set. The metadata consists of the rule set name and the
  timestamp of when the rule set was created.
  @return Returns a reference to this object so that method calls can be chained together.