Fix file-based ingestion flaky test

CHANGELOG.md

@@ -35,6 +35,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix issue with updating core with a patch number other than 0 ([#19377](https://github.com/opensearch-project/OpenSearch/pull/19377))
 - [Java Agent] Allow JRT protocol URLs in protection domain extraction ([#19683](https://github.com/opensearch-project/OpenSearch/pull/19683))
 - Fix potential concurrent modification exception when updating allocation filters ([#19701])(https://github.com/opensearch-project/OpenSearch/pull/19701))
+- Fix file-based ingestion consumer to handle start point beyond max line number([#19757])(https://github.com/opensearch-project/OpenSearch/pull/19757))
 
 ### Dependencies
 - Update to Gradle 9.1 ([#19575](https://github.com/opensearch-project/OpenSearch/pull/19575))

plugins/ingestion-fs/src/main/java/org/opensearch/plugin/ingestion/fs/FilePartitionConsumer.java

@@ -90,6 +90,7 @@ private synchronized List<ReadResult<FileOffset, FileMessage>> readFromFile(long
             }
 
             while (currentLineInReader < startLine && reader.readLine() != null) {
+                lastReadLine = currentLineInReader;
                 currentLineInReader++;
             }