if (comparisonSnapshot == null) {
comparisonDatabase = referenceSnapshot.getDatabase();
try {
comparisonSnapshot = new EmptyDatabaseSnapshot(referenceDatabase, referenceSnapshot.getSnapshotControl());
} catch (InvalidExampleException e) {
throw new UnexpectedLiquibaseException(e);
}
} else {
comparisonDatabase = comparisonSnapshot.getDatabase();
}
return getGenerator(referenceDatabase, comparisonDatabase).compare(referenceSnapshot, comparisonSnapshot, compareControl);