IMO, the real problem here is that

@ManyToOne(fetch=LAZY) @LazyToOne(NO_PROXY)

is a combination we just don’t support for polymorphic associations (and have never ever supported).

The previous behavior was to ignore fetch=LAZY, and give priority to NO_PROXY which was, well, better than the current behavior of ignoring NO_PROXY, since fetch is defines as a hint.

But I think that what should actually happen here is that we should throw, with a clear and helpful error message, since the mapping isn’t supported, and accepting it is misleading.