Error on index: MapperParsingException: No content is provided

Elastic Stack Elasticsearch
1

Some of my documents have attachments, some don't. Right now the ones that don't do not get indexed at all.

My mapping is:

@mapping=
{:priref=>{:type=>"integer", :index=>"not_analyzed"},
:title=>{:type=>"string"},
:publisher=>{:type=>"string"},
:keywords=>{:type=>"string"},
:abstract=>{:type=>"string"},
:digital_reference=>{:index=>"not_analyzed", :type=>"string"},
:language_code=>{:index=>"not_analyzed", :type=>"string"},
:year=>{:type=>"string"},
:material_type=>
{:analyzer=>"snowball", :index=>"not_analyzed", :type=>"string"},
:theme=>{:analyzer=>"snowball", :index=>"not_analyzed", :type=>"string"},
:created_at=>{:type=>"date", :index=>"not_analyzed"},
:updated_at=>{:type=>"date", :index=>"not_analyzed"},
:authors=>
{:type=>"object",
:properties=>{:name=>{:analyzer=>"snowball", :type=>"string"}}},
:attachment=>{:type=>"attachment", :store=>true}},
@options={:_source=>{:excludes=>["attachment"]}},
@type="document">

A few of my documents do not have an attachment. When indexing i get the following error:
MapperParsingException: No content is provided

Full error:

org.elasticsearch.index.mapper.MapperParsingException: No content is provided.
at org.elasticsearch.index.mapper.attachment.AttachmentMapper.parse(AttachmentMapper.java:371)
at org.elasticsearch.index.mapper.object.ObjectMapper.serializeNullValue(ObjectMapper.java:505)
at org.elasticsearch.index.mapper.object.ObjectMapper.parse(ObjectMapper.java:465)
at org.elasticsearch.index.mapper.DocumentMapper.parse(DocumentMapper.java:515)
at org.elasticsearch.index.mapper.DocumentMapper.parse(DocumentMapper.java:462)
at org.elasticsearch.index.shard.service.InternalIndexShard.prepareIndex(InternalIndexShard.java:384)
at org.elasticsearch.action.index.TransportIndexAction.shardOperationOnPrimary(TransportIndexAction.java:203)
at org.elasticsearch.action.support.replication.TransportShardReplicationOperationAction$AsyncShardOperationAction.performOnPrimary(TransportShardReplicationOperationAction.java:556)
at org.elasticsearch.action.support.replication.TransportShardReplicationOperationAction$AsyncShardOperationAction$1.run(TransportShardReplicationOperationAction.java:426)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)

How can i make sure the attachment is optional?

I'm using the Mapper attachments plugin and Elasticsearch 1.1.2

2

As described in this issue the content is not optional. What's unclear to my at the moment (and from reading the issue) is what happens if you don't index the field at all (in your case I think thats the "attachment" field?). How do you index your documents?