code: public Object invokeOptionalWithoutCheckedException(T target, Object... args) {
      try {
        return invokeOptional(target, args);
      } catch (InvocationTargetException e) {
        Throwable targetException = e.getTargetException();
        if (targetException instanceof RuntimeException) {
          throw (RuntimeException) targetException;
        }
        AssertionError error = new AssertionError("Unexpected exception");
        error.initCause(targetException);
        throw error;
      }
    }
docs: Invokes the method on {@code target}.  If the method does not exist or is not
  public then {@code null} is returned. Any RuntimeException thrown by the method is thrown,
  checked exceptions are wrapped in an {@link AssertionError}.
  
  @throws IllegalArgumentException if the arguments are invalid