We need to use WpSpaJson to parse the values in WpSettings. This is because the
wireplumber configuration is written in JSON, so WpSettings should only hold
JSON values. To fix this, 2 API changes have been done:
- wp_settings_get_int() only accepts gint values, instead of gint64 values. This
is because the WpSpaJson API only parses int values, like spa_json_parse_int().
- wp_settings_get_string() now returns a newly allocated string, this is because
the string needs to be decoded in case it has quotes.