code: private static Class<?> fromPrimitive(Class<?> clazz) {
  		Class<?> clazz2 = PRIMITIVE_TO_CLASS.get(clazz);
  		return clazz2 == null ? clazz : clazz2;
  	}
docs: Converts and returns the specified class, if it represents a primitive, to the associated
  non-primitive class, or else returns the specified class if it is not a primitive.
  
  @param clazz
  the input class
  @return the associated non-primitive class, or the input class if it is not a primitive