Proposed API for JEP 259: Stack-Walking API

[Brian Goetz]

> I considered Optional<Class<?>>. I believe it is rare to have a JNI attached thread calling StackWalker::getCallerClass from native.  Most common cases will find a caller class.   Returning an Optional will force most common uses to handle the case if it’s absent.  It’s a tradeoff that I think it’s better to return Thread.class for the JNI attached thread calling getCallerClass in native which would rarely happen.

+1 on returning Thread.class in these cases.  Its a pragmatic compromise.