I am somewhat familiar with the concept of packages in Java, but I’m new to WordPress and PHP.
In a template file such as header.php, what is happening when you include the @package notation?
<?php
/*
* @package MyTheme
*/
What difference does it make including the @package annotation or not?
Those are PHPDoc tags. They are entirely for code documentation purposes.
Nothing will happen. This PHPDoc tag has no special meaning in WordPress, it is not a header WordPress will parse by default. Use it to group your code internally.
get_file_data()cannot read it because that function needs a:after the identifier (herepackage).