Currently, NashornLinker will create a conditional ScriptObjectMirror converter for _any_ source type if the target type is something that a ScriptObjectMirror can be, e.g. Map. However, it'll do it even if the source type can never be a ScriptObject (e.g. java.lang.Double). This causes more matches in the "canConvert" too, which allows more candidates for overload resolution to pass. This has no significant effect, except for making more work for overload resolution, as well as causing a bunch of bogus converters to exist for (most notably) anything-to-Map.