code: public DescribeReservedElasticsearchInstancesResult withReservedElasticsearchInstances(ReservedElasticsearchInstance... reservedElasticsearchInstances) {
          if (this.reservedElasticsearchInstances == null) {
              setReservedElasticsearchInstances(new java.util.ArrayList<ReservedElasticsearchInstance>(reservedElasticsearchInstances.length));
          }
          for (ReservedElasticsearchInstance ele : reservedElasticsearchInstances) {
              this.reservedElasticsearchInstances.add(ele);
          }
          return this;
      }
docs: <p>
  List of reserved Elasticsearch instances.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setReservedElasticsearchInstances(java.util.Collection)} or
  {@link #withReservedElasticsearchInstances(java.util.Collection)} if you want to override the existing values.
  </p>
  
  @param reservedElasticsearchInstances
  List of reserved Elasticsearch instances.
  @return Returns a reference to this object so that method calls can be chained together.