This method is called by the REST output visitors to allow a field type to
post process the given $outgoingValueHash, which was previously generated
using {@link eZ\Publish\SPI\FieldType\FieldType::toHash()}, before it is
sent to the client. The return value of this method replaces
$outgoingValueHash and must obey to the same rules as the original
$outgoingValueHash.
См. также:
eZ\Publish\Core\REST\Common\Output\FieldTypeSerializer