Are defaults in JDK 8 a form of multiple inheritance in Java?

The answer to the duplicate operation is:

To solve multiple inheritance issue a class implementing two interfaces providing a default implementation for the same method name and signature must provide an implementation of the method. [Full Article]

My answer to your question is: Yes, it is a form of multiple inheritance, because you can inherit behavior from different parents. What's missing is to inherit states, i. e., attributes.

I know this is a old post, but as i'm working with this stuff...

You will have an error from the compiler, telling you that:

 class TimeTravelingStudent inherits unrelated defaults for present() from types Attendance and Timeline reference to present is ambiguous, both method present() in Timeline and method present() in Attendance match.