code: public static String getClassFileName(Class<?> clazz) {
  		Assert.notNull(clazz, "Class must not be null");
  		String className = clazz.getName();
  		int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR);
  		return className.substring(lastDotIndex + 1) + CLASS_FILE_SUFFIX;
  	}
docs: Determine the name of the class file, relative to the containing
  package: e.g. "String.class"
  @param clazz the class
  @return the file name of the ".class" file