code: private static String format(@Nullable final Class<?> expectedType, @Nullable final Class<?> actualType) {
  		final String expected = expectedType != null ? expectedType.getName() : NO_TYPE_PLACEHOLDER;
  		final String actual = actualType != null ? actualType.getName() : NO_TYPE_PLACEHOLDER;
  		return String.format(MESSAGE_WITH_TYPES, expected, actual);
  	}
docs: Returns the formatted string {@link IllegalInstanceOfArgumentException#MESSAGE_WITH_TYPES} with the given types.
  
  @param expectedType
  the expected class of the given argument
  @param actualType
  the actual class of the given argument
  @return a formatted string of message with the given argument name