Support for multiline values

[Márcio Almada]

Code says it all:

class Foo
{
    /**
     * @json_value json [
     *     "x", "y"
     * ]
     * @json_value json {
     *    "x": {
     *        "y": "z"
     *    }
     * }
     */
    private $strong_typed_fixture;
}