public Builder setStartOffset(long startOffset) {
            this.startOffset = startOffset;
            return this;
        }
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