@Override
    public String toString() {
        return "PartitionData(" +
                "partition=" + partition + "," +
                "stateEpoch=" + stateEpoch + "," +
                "startOffset=" + startOffset + "," +
                "errorCode=" + errorCode + "," +
                "errorMessage=" + errorMessage + "," +
                "leaderEpoch=" + leaderEpoch + "," +
                "stateBatches=" + stateBatches +
                ")";
    }
This class contains the data for a partition in the interface to {@link Persister}. The various interfaces
reflect the ways in which a subset of the data can be accessed for different purposes.
server-common/src/main/java/org/apache/kafka/server/group/share/PartitionData.java