It shows the amount of memory that would be freed if all references to a particular object removed and it were garbage collected, called the retained size. This would allow us to figure out what/why objects are being held onto and how to fix it. The output is a dominator tree of memory usage starting from the memory roots and sorted at every level by retained memory size. It is shown in XML so that you can collapse and expand introspection. It shows the retained size and the static shallow size for each object. The api is heap-dominator-tree (filename:String) which takes a filename for the xml file that is created and populated with the results.