Dynamic bytecode modification of classes and class hierarchies

Various systems and methods for dynamic bytecode modification of classes and class hierarchies are described herein. In various embodiments, a Java® agent is received at a launch of a Java® Virtual Machine (JVM®), the agent implementing a premain method, the premain method accepting a reference to an instrumentation instance. The instrumentation reference is then stored, a deployment container is initialized, and, within the deployment container, an instance of an application is created. The instrumentation reference is then provided to the application instance. A class transformer is then retrieved from a persistence provider, and the class transformer is wrapped by an O.R. Persistence Container Class Transformer, which is then registered with the instrumentation instance. A class to be transformed is passed to the class transformer, which dynamically modifies the bytecode of the class before the class is loaded by the JVM®.