This question was asked once in 2012. Again is there documentation of the methods on UnityPlayer?
So far I see pause(), stop(), etc methods but no documentation. Where is the documentation?
I expect they don’t want you to use it directly like that. If people start calling the Java methods directly, then they won’t be able to make necessary bug fixes that change those interfaces. If you need to get something done, and you’ve paid for Unity3d, work with them to address and support your needs.
The methods are discussed in Android Unity integration articles and blogs, so I think they are supported but not really enough documentation.