Data ingestion failure due to error `Numeric columns do not support multivalue rows`

SYMPTOM:

During data ingestion, it hits error 

2018-04-30T21:34:50,735 INFO [appenderator_persist_0] io.druid.segment.realtime.appenderator.AppenderatorImpl - Removing sink for segment[SEGMENT_NAME].
2018-04-30T21:34:50,758 ERROR [task-runner-0-priority-0] io.druid.indexing.overlord.ThreadPoolTaskRunner - Exception while running task[IndexTa
sk{id=index_SEGMENT, type=index, dataSource=DATASOURCE}]                                                   
java.lang.UnsupportedOperationException: Numeric columns do not support multivalue rows.
        at io.druid.segment.DoubleDimensionIndexer.processRowValsToUnsortedEncodedKeyComponent(DoubleDimensionIndexer.java:40) ~[druid-processing-0.12.0-iap7.jar:0.12.0-iap7]
        at io.druid.segment.DoubleDimensionIndexer.processRowValsToUnsortedEncodedKeyComponent(DoubleDimensionIndexer.java:33) ~[druid-processing-0.12.0-iap7.jar:0.12.0-iap7]
        at io.druid.segment.incremental.IncrementalIndex.toTimeAndDims(IncrementalIndex.java:555) ~[druid-processing-0.12.0-iap7.jar:0.12.0-iap7]
        at io.druid.segment.incremental.IncrementalIndex.add(IncrementalIndex.java:503) ~[druid-processing-0.12.0-iap7.jar:0.12.0-iap7]
        at io.druid.segment.realtime.plumber.Sink.add(Sink.java:157) ~[druid-server-0.12.0-iap7.jar:0.12.0-iap7]
        at io.druid.segment.realtime.appenderator.AppenderatorImpl.add(AppenderatorImpl.java:223) ~[druid-server-0.12.0-iap7.jar:0.12.0-iap7]
        at io.druid.segment.realtime.appenderator.BaseAppenderatorDriver.append(BaseAppenderatorDriver.java:293) ~[druid-server-0.12.0-iap7.jar:0.12.0-iap7]

ROOT CAUSE: 

A row containing multi value is found during date ingestion, and indexer does not know how to handle. 

WORKAROUND:

Create a dummy config for property`"listDelimiter"` under `parseSpec`. You can fill in any string as the value.

SOLUTION :

"parseSpec" : {
          "format" : "csv",
          "hasHeaderRow": true,
          "listDelimiter": "abc",
          "timestampSpec": {
            "column": "TimeStamp"
          },