protected String lastPendingInstant() {
        return this.ckpMetadata.lastPendingInstant();
    }
Returns the last pending instant time.
inlong-sort/sort-flink/sort-flink-v1.15/sort-connectors/hudi/src/main/java/org/apache/inlong/sort/hudi/sink/bulk/BulkInsertWriteFunction.java