`GuavaImmutableCollectionDeserializer` cannot deserialize an empty `Optional` from null

[jonfreedman]

The following test should pass

public void testImmutableListOfOptionals() throws IOException {
	ImmutableList<OptionalInt> list = MAPPER.readValue("[1,null,3]", new TypeReference<ImmutableList<OptionalInt>>() { });
	assertEquals(3, list.size());
	assertEquals(OptionalInt.of(1), list.get(0));
	assertEquals(OptionalInt.empty(), list.get(1));
	assertEquals(OptionalInt.of(3), list.get(2));
}

See #27

[cowtowncoder]

I assume this is verified against 2.9.9?

[jonfreedman]

I've verified against 2.9.6 but I checked your source, you need to change this line: https://github.com/FasterXML/jackson-datatypes-collections/blob/master/guava/src/main/java/com/fasterxml/jackson/datatype/guava/deser/GuavaImmutableCollectionDeserializer.java#L40

value = null;
becomes
value = valueDes.getNullValue(ctxt);

Same fix as 0fc5e8b#diff-3e1e6a8832674f14bb424827a0180c66L157

We have a copy of this specific class in our codebase so I had forgotten that you asked me to open a new issue until I went back through my github notifications.

[cowtowncoder]

Got it, thanks!