private function spanContextToString($traceId, $spanId, $parentId, $flags)
    {
        $parentId = $parentId ?? 0;
        return sprintf('%x:%x:%x:%x', $traceId, $spanId, $parentId, $flags);
    }
private function spanContextToString($traceId, $spanId, $parentId, $flags)
    {
        $parentId = $parentId ?? 0;
        return sprintf('%x:%x:%x:%x', $traceId, $spanId, $parentId, $flags);
    }
private function spanContextToString ( $ traceId , $ spanId , $ parentId , $ flags ) { $ parentId = $ parentId ?? 0 ; return sprintf ( '%x:%x:%x:%x' , $ traceId , $ spanId , $ parentId , $ flags ) ; }
Store a span context to a string.

@param int $traceId
@param int $spanId
@param int $parentId
@param int $flags
@return string
Store a span context to a string .