SegmentInsertAction incompatibility introduced in #2220

[nishantmonu51]

In #2220 we modified the returnTypeReference in SegmentInsertAction.

On overlord update, all existing tasks start to fail on parsing the result for segmentInsertAction.
Stack trace -

\ token\n at [Source: N/A; line: -1, column: -1]"
exceptionStackTrace: "java.lang.IllegalArgumentException: Can not deserialize instance\

\ of java.util.HashSet out of START_OBJECT token\n at [Source: N/A; line: -1,\
\ column: -1]\n\tat com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:2774)\n\
\tat com.fasterxml.jackson.databind.ObjectMapper.convertValue(ObjectMapper.java:2716)\n\
\tat com.fasterxml.jackson.databind.ObjectMapper.convertValue(ObjectMapper.java:2707)\n\
\tat io.druid.indexing.common.actions.RemoteTaskActionClient.submit(RemoteTaskActionClient.java:120)\n\
\tat io.druid.indexing.common.TaskToolbox.pushSegments(TaskToolbox.java:224)\n\
\tat io.druid.indexing.common.task.RealtimeIndexTask$TaskActionSegmentPublisher.publishSegment(RealtimeIndexTask.java:517)\n\
\tat io.druid.segment.realtime.plumber.RealtimePlumber$4.doRun(RealtimePlumber.java:555)\n\
\tat io.druid.common.guava.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:42)\n\
\tat java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)\n\
\tat java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)\n\
\tat java.lang.Thread.run(Thread.java:745)\nCaused by: com.fasterxml.jackson.databind.JsonMappingException:\
\ Can not deserialize instance of java.util.HashSet out of START_OBJECT token\n\
\ at [Source: N/A; line: -1, column: -1]\n\tat com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:148)\n\
\tat com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:762)\n\
\tat com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:758)\n\
\tat com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.handleNonArray(CollectionDeserializer.java:275)\n\
\tat com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:216)\n\
\tat com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:206)\n\
\tat com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:25)\n\
\tat com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:2769)\n\
\t... 10 more\n"
exceptionType: java.lang.IllegalArgumentException interval: 2016-05-02T15:00:00.000Z/2016-05-02T16:00:00.000Z

[nishantmonu51]

Since the overlord is updated first and then the peons, we need to preserve backwards compatibility for task actions response.

[gianm]

ah, yeah, good point. Ok, I guess that means we need a new action. We aren't going to be able to make a json array based return type compatible with a json object return type. I can send a PR for this in a bit if that sounds good.

[nishantmonu51]

sounds good.