According to an example implementation, a computer-readable storage medium, computer-implemented method and a system are provided to receive a first class, the first class indirectly implementing a first interface, wherein the first class extends a second class that directly implements the first interface, identify one or more directly implemented methods within the first class, determine a method signature for one or more of the directly implemented methods, estimate that the first class indirectly implements the first interface based on the method signatures for the one or more directly implemented methods, and instrument the first class based on the estimating that the first class indirectly implements the first interface.