public Snapshot getSnapshot(long epoch) {
        Snapshot snapshot = snapshots.get(epoch);
        if (snapshot == null) {
            throw new RuntimeException("No in-memory snapshot for epoch " + epoch + ". Snapshot " +
                "epochs are: " + epochsToString());
        }
        return snapshot;
    }
Gets the snapshot for a specific epoch.
server-common/src/main/java/org/apache/kafka/timeline/SnapshotRegistry.java