The present technology utilizes agents to monitor and report data from Java virtual machines (JVM) to a controller as part of application performance monitoring. When a JVM is loaded, code defining an interface for agents is loaded as well. A determination may be made as to whether the loaded agent implements the interface defined at the JVM. If the loaded agent does not implement the interface, for example if it is missing one or more methods defined by the interface, the agent class may be modified to define the missing methods. The modification to the agent class may be made after compilation but before the class is loaded into the JVM.