code: public DescribeDimensionKeysResult withPartitionKeys(ResponsePartitionKey... partitionKeys) {
          if (this.partitionKeys == null) {
              setPartitionKeys(new java.util.ArrayList<ResponsePartitionKey>(partitionKeys.length));
          }
          for (ResponsePartitionKey ele : partitionKeys) {
              this.partitionKeys.add(ele);
          }
          return this;
      }
docs: <p>
  If <code>PartitionBy</code> was present in the request, <code>PartitionKeys</code> contains the breakdown of
  dimension keys by the specified partitions.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setPartitionKeys(java.util.Collection)} or {@link #withPartitionKeys(java.util.Collection)} if you want
  to override the existing values.
  </p>
  
  @param partitionKeys
  If <code>PartitionBy</code> was present in the request, <code>PartitionKeys</code> contains the breakdown
  of dimension keys by the specified partitions.
  @return Returns a reference to this object so that method calls can be chained together.