Elasticsearch.YAML-tmLanguage

# [PackageDev] target_format: plist, ext: tmLanguage
---
name: Elasticsearch
scopeName: source.es
fileTypes: [es, json, mustache]
uuid: bd4306a8-862e-4fbb-a455-8c351164cf0d

patterns:
- name: comment.block.es
  begin: "{{!"
  end: "}}"

- name: source.es.embedded.json
  begin: "{{[{&>#^/]?"
  captures:
    '0': {name: entity.name.tag.es}
  end: "}?}}"
  patterns:
  - include: '#template_filter'

- include: source.json

repository:
  template_filter:
    patterns:
    - name: string.unquoted.tag-string.es
      match: "[a-zA-Z0-9_.]+"

...