code: public static ClassFile buildClassFile(String className,
                                             Class<?>[] classes, 
                                             String[] prefixes,
                                             int observerMode)
          throws IllegalArgumentException
      {
          return buildClassFile(className, classes, prefixes, null, observerMode);
      }
docs: Just create the bytecode for the merged class, but don't load it. Since
  no ClassInjector is provided to resolve name conflicts, the class name
  must be manually provided.  An optional implementation of the
  MethodInvocationEventObserver interface may be supplied.
  
  @param className name to give to merged class
  @param classes Source classes used to derive merged class
  @param prefixes Optional prefixes to apply to methods of each generated
  class to eliminate duplicate method names
  @param observeMethods boolean Enable function call profiling.