presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/util/ConcatPageSource.java/ConcatPageSource/getReadTimeNanos
class ConcatPageSource:    @Override
    public long getReadTimeNanos()
    {
        setup();
        return readTimeNanos + ((current != null) ? current.getReadTimeNanos() : 0);
    }