code: public ClusterList getClusters(String searchTag) throws FlickrException {
  
          Map<String, Object> parameters = new HashMap<String, Object>();
          parameters.put("method", METHOD_GET_CLUSTERS);
  
          parameters.put("tag", searchTag);
  
          Response response = transportAPI.get(transportAPI.getPath(), parameters, apiKey, sharedSecret);
          if (response.isError()) {
              throw new FlickrException(response.getErrorCode(), response.getErrorMessage());
          }
          ClusterList clusters = new ClusterList();
          Element clustersElement = response.getPayload();
          NodeList clusterElements = clustersElement.getElementsByTagName("cluster");
          for (int i = 0; i < clusterElements.getLength(); i++) {
              Cluster cluster = new Cluster();
              NodeList tagElements = ((Element) clusterElements.item(i)).getElementsByTagName("tag");
              for (int j = 0; j < tagElements.getLength(); j++) {
                  Tag tag = new Tag();
                  tag.setValue(((Text) tagElements.item(j).getFirstChild()).getData());
                  cluster.addTag(tag);
              }
              clusters.addCluster(cluster);
          }
          return clusters;
      }
docs: Search for tag-clusters.
  <p/>
  
  <p>
  This method does not require authentication.
  </p>
  
  @since 1.2
  @param searchTag
  @return a list of clusters