public function get_config_json( $filename ) {
		if ( isset( $this->loaded[ $filename ] ) ) {
			return $this->loaded[ $filename ];
		}

		$config = $this->path . 'config/' . $filename . '.json';

		if ( ! file_exists( $config ) ) {
			return null;
		}

		$contents = file_get_contents( $config );

		if ( false === $contents ) {
			return null;
		}

		return $this->loaded[ $filename ] = json_decode( $contents, true );
	}