code: public Shard getShard(String docId) {
          assertNotEmpty(docId, "docId");
          return client.couchDbClient.get(new DatabaseURIHelper(db.getDBUri()).path("_shards")
                          .path(docId).build(),
                  Shard.class);
      }
docs: Get info about the shard a document belongs to.
  
  @param docId document ID
  @return Shard info
  @see <a
  href="https://console.bluemix.net/docs/services/Cloudant/api/advanced.html#-get-database-_shards-"
  target="_blank">_shards</a>