code: public PartitionInfo partitionInfo(String partitionKey) {
          if (partitionKey == null) {
              throw new UnsupportedOperationException("Cannot get partition information for null partition key.");
          }
          URI uri = new DatabaseURIHelper(db.getDBUri()).partition(partitionKey).build();
          return client.couchDbClient.get(uri, PartitionInfo.class);
      }
docs: Get information about a partition in this database.
  
  @param partitionKey database partition key
  @return {@link com.cloudant.client.api.model.PartitionInfo} encapsulating the database partition info.
  @throws UnsupportedOperationException if called with {@code null} partition key.