public <T> T newProxy(
      T target, Class<T> interfaceType, long timeoutDuration, TimeUnit timeoutUnit) {
    checkNotNull(target);
    checkNotNull(interfaceType);
    checkNotNull(timeoutUnit);
    checkPositiveTimeout(timeoutDuration);
    checkArgument(interfaceType.isInterface(), "interfaceType must be an interface type");

    Set<Method> interruptibleMethods = findInterruptibleMethods(interfaceType);