nvim-treesitter/tests/query/highlights/hocon/test.conf

HOCON = Human-Optimized Config Object Notation
// ^ @field
//        ^ @string
//                       ^ @string
//                              ^ @string
//                                    ^ @string

"it's": "a JSON\nsuperset",
//       ^ @string
//             ^ @string.escape
//                        ^ @punctuation.delimiter

features: [
//      ^ @operator
//        ^ @punctuation.bracket
    less noisy / less pedantic syntax
//             ^ @string
    ability to refer to another part of the configuration
    import/include another configuration file into the current file
    a mapping to a flat properties list such as Java's system properties
    ability to get values from environment variables
    # ability to write comments
//  ^@ comment
//     ^ @comment
    // this is also a comment 
//  ^ @comment
//     ^ @comment
]

specs url: "https://github.com/lightbend/config/blob/master/HOCON.md"
includes: { 
  include required(file("~/prog/tree-sitter-hocon/grammar.js")) 
//         ^ @keyword
//^ @include
//                ^ @punctuation.bracket
//                                                           ^ @punctuation.bracket
  override = true
//            ^ @boolean
}

it's: ${it's}. A ${HOCON}
//    ^ @punctuation.special
//     ^ @punctuation.special
//          ^ @punctuation.special
//           ^ @string
//             ^ @string
//                ^ @punctuation.special
//                      ^ @punctuation.special

this.is.a."long.key" = null,
//  ^ @punctuation.delimiter
//     ^ @punctuation.delimiter
//       ^ @punctuation.delimiter
//                      ^ @constant.builtin
week  = 7 days 
//      ^ @number
//         ^ @keyword