Proxies return private properties in __sleep, which is not supported by PHP.

__sleep should not return private parent property names (see http://php.net/__sleep) this raises notices, and also results in the value of the property being 'N' (null) instead of keeping its value.

I am unfortunately stuck having to serialize proxies in my revision tracking, as doctrine seems to be currently ignoring the fetch="EAGER" I set on the related properties.

Proxies should use the Serializable interface, and not __sleep, or not return parent property names which are private, it serves no purpose, and is not supported by PHP itself anyway.

Also, if you keep __sleep, but do not return the parent property names, then it will only include the items you return, so it would be better to simply drop the __sleep method, I cannot actually see any useful purpose it serves.