code: public QueryResult selectUnique(String eventCollection, String targetProperty, Timeframe timeframe) throws IOException {
          Query queryParams = new Query.Builder(QueryType.SELECT_UNIQUE)
                  .withEventCollection(eventCollection)
                  .withTargetProperty(targetProperty)
                  .withTimeframe(timeframe)
                  .build();
          QueryResult result = execute(queryParams);
          return result;
      }
docs: Select Unique query with only the required arguments.
  Query API info here: https://keen.io/docs/api/#select-unique
  
  @param eventCollection     The name of the event collection you are analyzing.
  @param targetProperty     The name of the property you are analyzing.
  @param timeframe     The {@link RelativeTimeframe} or {@link AbsoluteTimeframe}.
  @return The select unique query response.
  @throws IOException If there was an error communicating with the server or
  an error message received from the server.