code: public java.util.List<String> getPreferredCacheClusterAZs() {
          if (preferredCacheClusterAZs == null) {
              preferredCacheClusterAZs = new com.amazonaws.internal.SdkInternalList<String>();
          }
          return preferredCacheClusterAZs;
      }
docs: <p>
  A list of EC2 Availability Zones in which the replication group's clusters are created. The order of the
  Availability Zones in the list is the order in which clusters are allocated. The primary cluster is created in
  the first AZ in the list.
  </p>
  <p>
  This parameter is not used if there is more than one node group (shard). You should use
  <code>NodeGroupConfiguration</code> instead.
  </p>
  <note>
  <p>
  If you are creating your replication group in an Amazon VPC (recommended), you can only locate clusters in
  Availability Zones associated with the subnets in the selected subnet group.
  </p>
  <p>
  The number of Availability Zones listed must equal the value of <code>NumCacheClusters</code>.
  </p>
  </note>
  <p>
  Default: system chosen Availability Zones.
  </p>
  
  @return A list of EC2 Availability Zones in which the replication group's clusters are created. The order of the
  Availability Zones in the list is the order in which clusters are allocated. The primary cluster is
  created in the first AZ in the list.</p>
  <p>
  This parameter is not used if there is more than one node group (shard). You should use
  <code>NodeGroupConfiguration</code> instead.
  </p>
  <note>
  <p>
  If you are creating your replication group in an Amazon VPC (recommended), you can only locate clusters
  in Availability Zones associated with the subnets in the selected subnet group.
  </p>
  <p>
  The number of Availability Zones listed must equal the value of <code>NumCacheClusters</code>.
  </p>
  </note>
  <p>
  Default: system chosen Availability Zones.