ConcurrentInitializer implementations can be instantiated and configured with allocation and release lambdas.

Hello everyone.

Currently there is no clean way to dispose of an object created with a LazyInitializer. Either you call initializer.get().dispose(); but if you've never used initializer before this will invoke a potentially expensive routine just so the object can be immediately disposed.

Or you cache the result of initializer.get(); and then dispose the object you have cached. This means the developer has to worry about concurrency issues when disposing the object, and looses all the benefits of LazyInitializer having a built in cache.

To fix this I propose that a new variant of LazyInitializer is created, this variant will allow you to call a dispose method which will close the LazyInitializer object and then it will, if the wrapped object has been initialized, run whatever disposal routine is provided.

I have created a pull request with a potential implementation here: https://github.com/apache/commons-lang/pull/1119