code: private void setArgumentValue(final Object value) {
          try {
              getUnderlyingField().set(getContainingObject(), value);
          } catch (final IllegalAccessException e) {
              throw new CommandLineException.ShouldNeverReachHereException(
                      String.format(
                              "Couldn't set field value for %s in %s with value %s.",
                              getUnderlyingField().getName(),
                              getContainingObject().toString(),
                              value.toString()),
                      e);
          }
      }
docs: Set the underlying field to the new value.