When the transformer is checking a class C which implements interfaces I1, I2 ... to see whether an interface rule applies to the class it also needs to look for rules attached to any interfaces I1', I1'', ..., I2', I2'' ... where I1 extends I1' ..., I1' extends I1'', I2 extends I2', etc. In other words the whole extends tree needs to be searched upwards (actually, it is potentially a directed acyclic graph, not a tree).

The same modification is requiring when searching for overriding rules where C is a subclass of C' and C' implements interfaces I1, I2 ...