Don't break user's code

One of the most used 3rd party libraries in the Java world must be Apache Commons Lang. Breaking client code should be avoided at all costs IMO, but they still do things like removing capitalise(String) πŸ‡¬πŸ‡§, because they want you to use capitalize(String) πŸ‡ΊπŸ‡Έ . But to what end? As Simen Sinek says: Start with Why. Why do you create a library like commons-lang? For your users. To make them more productive, right?

Now, you're successful, you've got thousands and thousands of users. You've "done it". People listen to you, you have some well deserved fame in the world of geeks. Time passes and you make a new major release and you do what? Remove methods that people depend on because ... what? Because it makes the API documentation prettier? Because your IDE now sorts the methods nicer? Why oh why?

getFullStackTrace(Throwable) is another one. You must use getStackTrace(Throwable), stupid. Sure. Thanks. And at the end of the day, what have we gained?

Or how about changing Validate#notNull(object, message) from throwing IllegalArgumentException to throwing NullPointerException? That's harmless, right? Throwing a NPE is so much more "correct", so that justifies breaking a few thousand lines of user's code, isn't it?

I've come to deeply respect large projects that retain backwards compatibility at almost any cost: Wordpress, GNU coreutils, the Linux kernel and Oracle Java.

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