src/Zipkin/Propagation/Map.php
public function get($carrier, string $key): ?string
    {
        $lKey = strtolower($key);

        if ($carrier instanceof ArrayAccess) {
            return $carrier->offsetExists($lKey) ? $carrier->offsetGet($lKey) : null;
        }

        if (is_array($carrier)) {
            return array_key_exists($lKey, $carrier) ? $carrier[$lKey] : null;
        }

        throw InvalidPropagationCarrier::forCarrier($carrier);
    }
public function get($carrier, string $key): ?string
    {
        $lKey = strtolower($key);

        if ($carrier instanceof ArrayAccess) {
            return $carrier->offsetExists($lKey) ? $carrier->offsetGet($lKey) : null;
        }

        if (is_array($carrier)) {
            return array_key_exists($lKey, $carrier) ? $carrier[$lKey] : null;
        }

        throw InvalidPropagationCarrier::forCarrier($carrier);
    }
{@inheritdoc}
@param array|ArrayAccess $carrier