code: public Membership getMembership() {
          URI uri = new URIBase(getBaseUri()).path("_membership").build();
          Membership membership = couchDbClient.get(uri,
                  Membership.class);
          return membership;
      }
docs: Get the list of all nodes and the list of active nodes in the cluster.
  
  @return Membership object encapsulating lists of all nodes and the cluster nodes
  @see <a
  href="https://console.bluemix.net/docs/services/Cloudant/api/advanced.html#-get-_membership-">
  _membership</a>