关于在String类型下写入"2016-09-00"报 MapperParsingException

我在更新es数据时，写入一个”2016-09-00“的字符串，到birthdate字段，该字段已定义为string , not_analyzed。却报了一个MapperParsingException的错。
另外，我已经在mapping里设置了模板，默认type为string,not_analyzed.
详细报错如下：

MapperParsingException[failed to parse [birthdata]]; nested: IllegalArgumentException[Cannot parse "1983-09-00": Value 0 for dayOfMonth must be in the range [1,30]];

at org.elasticsearch.index.mapper.FieldMapper.parse(FieldMapper.java:329)

at org.elasticsearch.index.mapper.DocumentParser.parseObjectOrField(DocumentParser.java:309)

at org.elasticsearch.index.mapper.DocumentParser.parseValue(DocumentParser.java:436)

at org.elasticsearch.index.mapper.DocumentParser.parseObject(DocumentParser.java:262)

at org.elasticsearch.index.mapper.DocumentParser.parseDocument(DocumentParser.java:122)

at org.elasticsearch.index.mapper.DocumentMapper.parse(DocumentMapper.java:309)

at org.elasticsearch.index.shard.IndexShard.prepareIndex(IndexShard.java:580)

at org.elasticsearch.index.shard.IndexShard.prepareIndexOnPrimary(IndexShard.java:559)

at org.elasticsearch.action.index.TransportIndexAction.prepareIndexOperationOnPrimary(TransportIndexAction.java:212)

at org.elasticsearch.action.index.TransportIndexAction.executeIndexRequestOnPrimary(TransportIndexAction.java:224)

at org.elasticsearch.action.index.TransportIndexAction.shardOperationOnPrimary(TransportIndexAction.java:158)

at org.elasticsearch.action.index.TransportIndexAction.shardOperationOnPrimary(TransportIndexAction.java:66)

at org.elasticsearch.action.support.replication.TransportReplicationAction$PrimaryPhase.doRun(TransportReplicationAction.java:639)

at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37)

at org.elasticsearch.action.support.replication.TransportReplicationAction$PrimaryOperationTransportHandler.messageReceived(TransportReplicationAction.java:279)

at org.elasticsearch.action.support.replication.TransportReplicationAction$PrimaryOperationTransportHandler.messageReceived(TransportReplicationAction.java:271)

at org.elasticsearch.transport.RequestHandlerRegistry.processMessageReceived(RequestHandlerRegistry.java:75)

at org.elasticsearch.transport.TransportService$4.doRun(TransportService.java:376)

at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)

at java.lang.Thread.run(Thread.java:745)

Caused by: java.lang.IllegalArgumentException: Cannot parse "1983-09-00": Value 0 for dayOfMonth must be in the range [1,30]

at org.joda.time.field.FieldUtils.verifyValueBounds(FieldUtils.java:234)

at org.joda.time.field.PreciseDurationDateTimeField.set(PreciseDurationDateTimeField.java:79)

at org.joda.time.format.DateTimeParserBucket$SavedField.set(DateTimeParserBucket.java:568)

at org.joda.time.format.DateTimeParserBucket.computeMillis(DateTimeParserBucket.java:447)

at org.joda.time.format.DateTimeParserBucket.doParseMillis(DateTimeParserBucket.java:182)

at org.joda.time.format.DateTimeFormatter.parseMillis(DateTimeFormatter.java:780)

at org.elasticsearch.index.mapper.core.DateFieldMapper$DateFieldType.parseStringValue(DateFieldMapper.java:362)

at org.elasticsearch.index.mapper.core.DateFieldMapper.innerParseCreateField(DateFieldMapper.java:528)

at org.elasticsearch.index.mapper.core.NumberFieldMapper.parseCreateField(NumberFieldMapper.java:241)

at org.elasticsearch.index.mapper.FieldMapper.parse(FieldMapper.java:321)

... 21 more

这是不是一个bug？到底是什么原因？我用的是2.3.3版本