If I go to the Javadoc page for the RandomGenerator class I see a summary of the class constructor and methods. It says public class RandomGenerator extends Random.
How can I find out more information about how RandomGenator class invokes the constructor of Random class? I don't see any references in RandomGenerator class to it's superclass constructor.
Most likely you have to contact authors. For some reason they decided not to include this information into javadoc (public contract).
You may also look into class sources or use java decompiler if you don't have sources.
In case class constructor doesn't call super() directly that means that superclass has no-argument constructor which call is the first line of your class constructor always, and you do not need to call it explicitly.
P. S. My answer has two different approaches. I apologize for that, I just not quite sure whether you have sources for analysis.