How to create an Elasticsearch mapping with not_analyzed nested fields?

Elastic Stack Elasticsearch
1

How do I create a mapping with nested fields, where the nested fields are not_analyzed?

I can't figure out the correct mapping, see my example below.

Data which is indexed into the fields taxonomyHMG.0, taxonomyHMG.1,
taxonomyHMG.2, etc. is processed through the standard tokenizer (can be
tested by running a facet query).

This happens although all the nested fields are set to "not_analyzed". I am running ES 1.4.5. What am I missing?

    "taxonomyHMG": {
            "properties": {
            0: {
                "type": "string","index": "not_analyzed"
            },
            1: {
                "type": "string","index": "not_analyzed"
            },
            2: {
                "type": "string","index": "not_analyzed"
            },
            3: {
                "type": "string","index": "not_analyzed"
            },
            4: {
                "type": "string","index": "not_analyzed"
            },
            5: {
                "type": "string","index": "not_analyzed"
            },
            5: {
                "type": "string","index": "not_analyzed"
            },
            }