public boolean isEmpty() {
    return defaultBatch.isEmpty()
        && endPointToBatch.values().stream().allMatch(PipeTabletEventPlainBatch::isEmpty);
  }
Get all batches that have at least 1 event.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/payload/evolvable/batch/PipeTransferBatchReqBuilder.java