code: public Object getArgumentValue() {
          try {
              return getUnderlyingField().get(getContainingObject());
          } catch (final IllegalAccessException e) {
              throw new CommandLineException.ShouldNeverReachHereException(
                      "This shouldn't happen since we setAccessible(true).", e);
          }
      }
docs: Get the {@code Object} representing the current value of the field for this object.
  @return A boxed value even if the underlying field is a primitive. will not be null.