Requests need to account for undefined index pattern title

[jbudz]

The index pattern _id field used to be the source for the pattern to query elasticsearch. At some point we added a title field to contain the pattern. In 5.6 the .kibana index expects this field to be defined, but older versions of the index may not have it.

Errors include [null_pointer_exception] index must not be null and pattern" fails because ["pattern" is required]. We need to make sure we fall back to the id if a title is not defined.

workaround options:

• update index patterns to have a title:

POST .kibana/index-pattern/_update_by_query
{
    "script" : {
        "source": "if (ctx._source.title == null) ctx._source.title = ctx._id",
        "lang": "painless"
    }
}

• deleting and re-adding index patterns in the kibana ui. note this will require any scripted fields or field formatters to be recreated

[jbudz]

Closed by #14302