default <T> T firstRecord(Class<T> objClass) {
        return records(objClass).iterator().next();
    }
Gets the first record as mapped object. Please use {@link #records(Class)}
instead if you need to access the rest of records.

@param <T>      type of the mapped object
@param objClass non-null class of the mapped object
@return mapped object of the first record
@throws NoSuchElementException when there's no record at all
@throws UncheckedIOException   when failed to read data(e.g. deserialization)
clickhouse-client/src/main/java/com/clickhouse/client/ClickHouseResponse.java