code: public static <T> void isInstanceOf (@Nullable final T aValue,
                                         @Nonnull final Class <? extends T> aClass,
                                         final String sMsg)
    {
      if (isEnabled ())
        isInstanceOf (aValue, aClass, () -> sMsg);
    }
docs: Check that the passed value is an instance of the passed class.
  
  @param aValue
  The value to check. May be <code>null</code>.
  @param aClass
  The class of which the passed value must be an instance. May not be
  <code>null</code>.
  @param sMsg
  The message to be emitted in case the value is <code>false</code>
  @throws IllegalArgumentException
  if the passed value is not <code>null</code>.
  @param <T>
  Type to check.