SnapshotMeta
data class SnapshotMeta(val lastIncludedIndex: Long, val lastIncludedTerm: Long, val config: ConfigPayload? = null)
Identifies the log position a snapshot covers: everything with index <= lastIncludedIndex.
config is the effective cluster configuration as of lastIncludedIndex — the membership a node must adopt when it installs this snapshot, since the config log entries that produced it were discarded by compaction. null means the covered prefix carried no config change (the cluster was still under its bootstrap configuration); a non-null ConfigPayload may be simple (old == null) or joint (old != null), so a snapshot taken mid-transition resumes the joint phase on install.