Method references are specified (0.6.2 Lambda Spec) to be resolved without regard to the 'static' flag of the candidate method(s). This is highly unintuitive and leads to spurious errors, especially when unbound method references ("String::substring") are used. Most people do not understand it, or even account for it in their mental model.

Without violating the spirit of method resolution (which allows, for example, a static method to "shadow" an instance method), method reference resolution should be more intelligent.