NullPointerException is thrown when using MongoTemplate.findAndModify(...) with @DbRef and interface as @DbRef target. See attached project for more details. Probably regression issue since same test is passing with Spring Data Commons 1.6.3.RELEASE and Spring Data MongoDB 1.3.3.RELEASE.
In 1.4 DBRef resolution in QueryMapper changed in a way that tries to inspect if the properties Id can be assigned to the given type. When one passes in an Update it is most likely not to have all type information at hand, which means in case of an property pointing to an interface that the entire resolution might have failed.
In 1.5 it`s possible to resolve properties on interfaces as long as those follow the beans convention. But it failed, as it does in 1.4.x, for those properties not having the required getters
I've force-pushed the branch to rebase it against the latest changes? Any chance we can get a test case on the QueryMapper level instead of the one in MongoTemplateTests. The latter is more and more becoming some kind of kitchen sink for all sorts of tests for changes that seem to be totally unrelated to actual type