@Internal
    @Override
    public SplitEnumerator<PulsarPartitionSplit, PulsarSourceEnumState> restoreEnumerator(
            SplitEnumeratorContext<PulsarPartitionSplit> enumContext,
            PulsarSourceEnumState checkpoint) {
        return new PulsarSourceEnumerator(
                subscriber,
                startCursor,
                stopCursor,
                rangeGenerator,
                sourceConfiguration,
                enumContext,
                checkpoint);
    }
Get a PulsarSourceBuilder to builder a {@link PulsarSource}.

@return a Pulsar source builder.
inlong-sort/sort-flink/sort-flink-v1.15/sort-connectors/pulsar/src/main/java/org/apache/inlong/sort/pulsar/source/PulsarSource.java