Neos\Flow\Core\Migrations\AbstractMigration::getIdentifier PHP Method

    public abstract function getIdentifier();

function outputMigrationHeadline(AbstractMigration $migration)
{
    global $lastMigration;
    if ($migration !== $lastMigration) {
        outputHeadline('Migration %s (%s)', 1, array($migration->getIdentifier(), formatVersion($migration->getVersionNumber())));
        $description = $migration->getDescription();
        if ($description !== null) {
            outputLine($description);
            outputLine();
        }
        $lastMigration = $migration;
    }
}