commit f258da6b07b6c2ca1998b2bef205af62c7286d67
author Géraud Dugé de Bernonville <geraudster@gmail.com> Sun May 26 14:16:51 2019 +0200
committer Sijie Guo <sijie@apache.org> Sun May 26 20:16:51 2019 +0800
tree 15a766c5128130e843ecc447d5f8488026d7c816
parent 37e324732a92edda554f76647a2b84825c299387

[pulsar-io-elastic-search] Change default document type for compliance with ES 7.x (#4322)

### Motivation

When running Elasticsearch sink on ES 7.0.1, message indexation fails with the following error :

```
- Encountered exception in sink write: 
org.elasticsearch.ElasticsearchStatusException: Elasticsearch exception [type=illegal_argument_exception, reason=Rejecting mapping update to [geoloc-pulsar] as the final mapping would have more than 1 type: [_doc, doc]]
```

According to https://www.elastic.co/guide/en/elasticsearch/reference/6.3/removal-of-types.html#_schedule_for_removal_of_mapping_types, the recommended document type to use is `_doc`.

### Modifications

Replace document type `doc` with recommended value `_doc`.