@VisibleForTesting
    Map<KafkaTopicPartition, Long> getSubscribedPartitionsToStartOffsets() {
        return subscribedPartitionsToStartOffsets;
    }
Creates the partition discoverer that is used to find new partitions for this subtask.

@param topicsDescriptor Descriptor that describes whether we are discovering partitions for
        fixed topics or a topic pattern.
@param indexOfThisSubtask The index of this consumer subtask.
@param numParallelSubtasks The total number of parallel consumer subtasks.
@return The instantiated partition discoverer
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/kafka/src/main/java/org/apache/inlong/sort/kafka/FlinkKafkaConsumerBase.java