Reindex API doesn't index .percolator documents unless explicitly specified

Elastic Stack Elasticsearch
1

Hey all,
I'm using ES 2.3.2, we have used Reindex API couple of times to index documents of all the mapping types to new index. It skips .percolator type documents unless you specify that explicitly.

For ex:

POST /_reindex?refresh&wait_for_completition=false
{
   "source": {
      "index": "prod-small-1",
      "size": 5000
   },
   "dest": {
      "index": "prod-small-0"
   }
}

prod-small-1 has mapping types test1, test2 and .percolator.
After executing above query only test1 and test2 mapping type documents are indexed into prod-small-0 index.
Ideally if you don't specify any mapping type it should index documents from all mapping types.

I'm not sure if this is the expected behavior or it's a bug.
If it's a expected behavior, I would suggest adding this to the Reindex API documentation.

Thanks,
Ayush Sangani