code: @SuppressWarnings("unchecked")
      public Class<? extends T> defineClass() {
          if (generatedClass == null) {
              synchronized (this) {
                  if (generatedClass == null) {
                      try {
                          // first check that the proxy has not already been created
                          generatedClass = (Class<? extends T>) classLoader.loadClass(this.className);
                      } catch (ClassNotFoundException e) {
                          buildClassDefinition();
                          if (protectionDomain == null) {
                              generatedClass = (Class<? extends T>) classFile.define();
                          } else {
                              generatedClass = (Class<? extends T>) classFile.define(protectionDomain);
                          }
                          afterClassLoad(generatedClass);
                      }
                      classFile = null;
                  }
              }
          }
          return generatedClass;
      }
docs: Returns the {@link Class} object for the generated class, creating it if it does not exist
  
  @return the generated class