When field is null, dont serialise it

[ManiSingal]

Hi so I have the following classes

public class report {
    private HeaderInfo HeaderInfo;
    private TimeInfo TimeInfo;
    private MsgInfo MsgInfo;

    public String toJson() {
        final ObjectMapper mapper = new ObjectMapper();
        mapper.setSerializationInclusion( JsonInclude.Include.NON_NULL);
        
        SimpleModule simpleModule = new SimpleModule();
        simpleModule.addSerializer( Foo.class, new TimeSerializer( m_timeZone );
        mapper.registerModule(simpleModule);
        
        try {
            return mapper.writeWithDefaultPrettyPrinter().writeValueAsString(this);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
    }
}

public class HeaderInfo {
    private String fieldOne;
    private String fieldTwo;
    private TimeField timeFieldThree;
    private Timezone timeZone;
}

public class TimeInfo {
    private TimeField timeFieldOne;
    private TimeField timeFieldTwo;
}

public class MsgInfo {
    private long fieldOne;
    private long fieldTwo;
}

public class TimeField {
    private Long m_time;
}

Now inside the report classes, I have some time fields, which I want to serialize differently, so I've made a custom serializer class

public static class TimeFieldSerializer implements JsonSerializer<TimeField> {
    private TimeZone m_timeZone;

    public TimeFieldSerializer(final TimeZone timeZone) {
        m_timeZone = timeZone;
   }

    @Override
    public void serialize(final TimeField value, final JsonGenerator gen, final SerializerProvider serializers)
            throws IOException {
        if (value.getTime() == null) {
            // dont include it
        } else {
            final String timestamp = Nanos.toString(value.getTime(), timeZone);
            gen.writeString(timestamp);
        }
    }
}

The issue is that when I don't write any value in the custom serializer, i get a JsonGeneratorException: Can not write a field name, expecting a value. But when I write null, it shows up as null in the Json Output. How do I get it to not serialize it at all. I think the issue is the level I'm doing the serialization at. I should be doing the serialization at the class level, but the issue is that when serializing I need to pass it the timezone variable, so the only way to do that is to add it as a module. Is there a solution to this, or is this a limitation in the library?