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TL;

While investigating https://github.com/apache/shardingsphere/pull/29384 , I noticed that without setting @JsonCreator for the POJO, the required attribute in @JsonProperty is not checked.

I created a minimal unit test at https://github.com/linghengqian/jackson-xml-required-check-test . The core code looks like this.

public class RequiredTest {
@Test
void assertRequiredValue() {
    ObjectMapper XML_MAPPER = XmlMapper.builder().build();
    assertThrows(MismatchedInputException.class, () -> XML_MAPPER.readValue("<Record></Record>", TestRecord.class));
    assertThrows(MismatchedInputException.class, () -> XML_MAPPER.readValue("<TR></TR>", TestRecordWithoutCreator.class));
}

@Getter
@NoArgsConstructor
@JacksonXmlRootElement(localName = "Record")
static class TestRecord {
    private String type;

    private String driverClassName;

    @JsonCreator
    public TestRecord(
            @JsonProperty(required = true) @JacksonXmlProperty(localName = "type", isAttribute = true)
            String type,
            @JsonProperty(required = true) @JacksonXmlProperty(localName = "driverClassName")
            String driverClassName) {
        this.type = type;
        this.driverClassName = driverClassName;
    }
}

@Getter
@JacksonXmlRootElement(localName = "TR")
static class TestRecordWithoutCreator {
    @JsonProperty(required = true)
    @JacksonXmlProperty(localName = "type", isAttribute = true)
    private String type;

    @JsonProperty(required = true)
    @JacksonXmlProperty(localName = "driverClassName")
    private String driverClassName;
}
}

assertThrows(MismatchedInputException.class, () -> XML_MAPPER.readValue("<TR></TR>", TestRecordWithoutCreator.class)); will not throw any exception.

[ERROR] com.lingh.RequiredTest.assertRequiredValue -- Time elapsed: 0.276 s <<< FAILURE!
org.opentest4j.AssertionFailedError: Expected com.fasterxml.jackson.databind.exc.MismatchedInputException to be thrown, but nothing was thrown.
        at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:152)
        at org.junit.jupiter.api.AssertThrows.assertThrows(AssertThrows.java:73)
        at org.junit.jupiter.api.AssertThrows.assertThrows(AssertThrows.java:35)
        at org.junit.jupiter.api.Assertions.assertThrows(Assertions.java:3115)
        at com.lingh.RequiredTest.assertRequiredValue(RequiredTest.java:21)
        at java.base/java.lang.reflect.Method.invoke(Method.java:568)
        at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
        at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)

Did I misunderstand something while reading the documentation?

FasterXML / jackson-dataformat-xml

Without setting `@JsonCreator` for the POJO, the `required` attribute in `@JsonProperty` is not checked #625

TL;