If an interface implements another interface, any class implementing the second interface won't have any interface methods automatically generated by Umple.
Also, if an interface has the above problem, and class extending it will also have the problem (this is a separate issue).
Try generating Java from InterfaceTemplateTest.ump using Umple online. Any class that implements ISecondChild has this problem.
All interface methods should be generated
None are being generated
I have a fix for this. Will put together a PR tomorrow.