Non default value skipped in serialized json with serialization inclusion NON_DEFAULT

Running following code:

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;

public class Test {

	@org.junit.Test
	public void name() throws Exception {
		ObjectMapper mapper = new ObjectMapper();
		mapper.setSerializationInclusion(JsonInclude.Include.NON_DEFAULT);

		Pojo pojo = new Pojo();
		pojo.setValue(false);

		System.out.println(mapper.writeValueAsString(pojo));
	}

	public static class Pojo {
		private Boolean value;

		public Boolean getValue() {
			return value;
		}

		public void setValue(Boolean value) {
			this.value = value;
		}
	}
}

with Jackson v 2.8.2 outputs {"value":false} (as I expected). This however changes starting with 2.8.3: it outputs {} (tested with 2.8.3, 2.8.11.2 and 2.9.6). I guess it was affected by #1351. Was it intended? Imo that’s bug: default value for Boolean is null, not false.

[workmanw]

This issue also burned us when upgrading from 2.6.6 to 2.9.6. It was extra confusing because of the breaking changes with NON_EMPTY and NON_DEFAULT going from 2.6.x to 2.7.x+.

This also changed with String. Previously "" would not be omitted with `NON_DEFAULT. After 2.8.3 it is omitted.

I’m reading a bunch of other tickets relating #1351 and I’m sympathetic because it’s hard to know what the right answer is. But it would be great to know if this is a bug that’s going to be fixed (and thus we might upgrade to 2.8.2) or if this is future functionality and we need to fix this in our application.

[cowtowncoder]

@Rolly992 what you think is “default value” is not actually specification of what Jackson means by default PROPERTY value for deserialization purposes. Before sharing your personal interpretation of a term it makes sense to try to learn its meaning in context.

But to recap: idea of default value for, say

public class MyValue {
   public int x, y;

   public MyValue() {
        x = 3;
        y = 7;
   }

   // getters and setters

is that default value for x is 3, and y is 7 (in context of “property value of MyValue”). This because default instance of MyValue would have those values. But implementing this can get tricky because to find real default values – and not just what JDK initializes properties to, in absence of assignment – one needs to have containing POJO type.