Changed:
- Replaced `array_map()` with `foreach` to maintain support for array keys while allowing easy exclusion of attributes.

Fixed:
- Superfluous spaces by ignoring NULL values.
- Support for boolean values from callable values.
- Support for numeric (integer and float) values not always rendering.

Added:
- Condition to trim leading and trailing whitespace from the array key.
- Condition to ignore any empty array key.

Fixed:
- Lack of support for objects as affirmed in the README.

Changed:
- Removed unnecessary call to `jsonSerialize()` method when directly used with `json_encode()`
- Replaced `call_user_func()` with direct calling of `$callback`

Changed:
- Hard-wrapped lines to ~80 characters for consistent reading.
- Updated version information to indicate function is compatible with PHP 7 and PHP 8.
- Improved description of parameters and return values.
- Replaced inline links with reference links.