Root-level `null` handling (via `xsi:nil`) leaves trailing token in `JsonParser`-exposed token stream

[cowtowncoder]

(note: issue uncovered due to FasterXML/jackson-databind#3406 change to default of DeserializationFeature.FAIL_ON_TRAILING_TOKENS to true).

So: it looks like conversion of root XML object into virtual null (using xsi:nil at least) produces unwanted JsonToken.END_OBJECT token, caught by validation.
Ideally this would not occur.