public String toString() {
        return "ShareSession(" +
                "key=" + key +
                ", partitionMap=" + partitionMap +
                ", creationMs=" + creationMs +
                ", lastUsedMs=" + lastUsedMs +
                ", epoch=" + epoch +
                ", cachedSize=" + cachedSize +
                ")";
    }
The share session.
Each share session is protected by its own lock, which must be taken before mutable
fields are read or modified.  This includes modification of the share session partition map.

@param key                The share session key to identify the share session uniquely.
@param partitionMap       The CachedPartitionMap.
@param creationMs         The time in milliseconds when this share session was created.
@param lastUsedMs         The last used time in milliseconds. This should only be updated by
                          ShareSessionCache#touch.
@param epoch              The share session sequence number.
server/src/main/java/org/apache/kafka/server/share/ShareSession.java