Improve source browser navigation for deeply nested directory structures (BB-10686)

In Java, projects often have directories with dig depths because of the name spacing in Java. For instance, if my project is called powerBucket and I created it, the namespace will be: de.matt3o12.powerBucket. Java requires me to put all my classes with that namespace into "de/matt3o12/powerBucket". So, the project hierarchy will look like this:

src/
	de/
		matt3o12/
			powerBucket/
				MyClass.java
				... other classes
	

Navigating to MyClass.java in bitbucket can really be a hassle. All folders (except powerBucket) are often empty or just contain some unimportant files.

Since navigation to MyClass (especially with slow internet) is very time consuming, it would be nice if I could access the subdirectory powerBucket directly.
Jenkins provides a decent way to do so. When a folder contains a subfolder (and only one), it displays all subfolder next to the main folder. I attached 2 screenshots what it looks like in Jenkins and how it could look in bitbucket (I manipulated the HTML).