JsonTypeId-only class is not serialized properly

[alexzam]

I have this code:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type")
@JsonSubTypes({
        @JsonSubTypes.Type(value = A.class, name="suppressed")
})
interface I{}

class A implements I {
    @JsonTypeId
    public String getType(){
        return "goodA";
    }
}

After serialization of new A() in field of type I I expect to get {type: "goodA"}, but instead I get {type: "suppressed"}.
But if I add any other property to A (like public int getFake() {return 0;}) then serialization works right (and I get {type: "goodA", fake: 0}).

That's because BeanSerializerBuilder.build() exits if no "real" properties present ignoring _typeId:

    if (_properties == null || _properties.isEmpty()) {
            if (_anyGetter == null && _objectIdWriter == null) {
                return null; 
...

Found in 2.9.5 but code is not changed up to 2.9.7

[cowtowncoder]

Can no longer reproduce with 3.0.0, issue considered resolved.