Whitespace string is considered `null` when deserializing to primitive

Describe the bug Setting whitespace string to an int property while ALLOW_COERCION_OF_SCALARS and ACCEPT_EMPTY_STRING_AS_NULL_OBJECT are disabled, results in Cannot coerce null to int error, while empty string is considered an actual string in that case. This could potentially become a problem if int was changed to Integer. In that case json will be successfully parsed for whitespace string and fail for empty.

Might be related to https://github.com/FasterXML/jackson-databind/issues/3234

Version information 2.13.3

To Reproduce Mapper builder

new Jackson2ObjectMapperBuilder()
    .featuresToDisable(MapperFeature.ALLOW_COERCION_OF_SCALARS)
    .featuresToDisable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT)
    .featuresToDisable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY)
    .featuresToDisable(DeserializationFeature.UNWRAP_SINGLE_VALUE_ARRAYS)
    .featuresToEnable(DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES)
    .featuresToEnable(DeserializationFeature.FAIL_ON_MISSING_CREATOR_PROPERTIES);

Test code

test("\"\"");
test("\" \"");
test("\"    \"");
test("\"\\n\"");

void test(String value) throws Exception {
    System.out.println("{\"value\":" + value + "}");
    try {
        Model model = OM.readValue("{\"value\":" + value + "}", Model.class);
    } catch (JsonMappingException e) {
        System.out.println(e.getLocalizedMessage());
    }
}

public class Model {
    private int value;

    public Model() {
    }

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

    public int getValue() {
        return this.value;
    }
}

Output

{"value":""}
Cannot coerce empty String ("") to `int` value (but could if coercion was enabled using `CoercionConfig`)
 at [Source: (String)"{"value":""}"; line: 1, column: 10] (through reference chain: test.MainTest$Model["value"])
{"value":" "}
Cannot coerce `null` to `int` value (disable `DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES` to allow)
 at [Source: (String)"{"value":" "}"; line: 1, column: 10] (through reference chain: test.MainTest$Model["value"])
{"value":"    "}
Cannot coerce `null` to `int` value (disable `DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES` to allow)
 at [Source: (String)"{"value":"    "}"; line: 1, column: 10] (through reference chain: test.MainTest$Model["value"])
{"value":"\n"}
Cannot coerce `null` to `int` value (disable `DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES` to allow)
 at [Source: (String)"{"value":"\n"}"; line: 1, column: 10] (through reference chain: test.MainTest$Model["value"])

Expected behavior Whitespace string should be handled as any other string.

[cowtowncoder]

@bigboynaruto I don’t know where Jackson2ObjectMapperBuilder comes from, but since it’s not part of databind it might not have access to this configuration. However: ObjectMapper.copy() should copy these settings, so if that is being used, coercion configs should come along. If not that’d be a bug, and we’d appreciate a simple test case to show this (there are some tests for ObjectMapper.copy() to try to find other problems, but not yet (I think) for coercion configs).

Jackson 3.0 (from master) has much better way to deal with builders, but alas it’s still some way off.

[yawkat]

It’s caused by this code: https://github.com/FasterXML/jackson-databind/blob/c100ed5b3bbb2ae7d1287ae368672469a1bafd0c/src/main/java/com/fasterxml/jackson/databind/cfg/CoercionConfigs.java#L310-L314

Looks like it is necessary for compatibility, however specifying an explicit coercion config for the type should work fine.