这个问题是关于JacksonXMLMap序列化和非序列化的。默认情况下，Jackson希望Map的键是XML元素本身。

<MyMap>
    <key1>value1</key1>
    <key2>value2</key2>
</MyMap>

但这使得不可能有无效XML元素名称的键。
在Jackson中，是否有一种方法可以通过 Package 条目XML元素（如下所示）将XML封装起来？

<MyMap>
    <MyEntry>
        <Key>key1</Key>
        <Value>value1</Value>
    </MyEntry>
    <MyEntry>
        <Key>key2</Key>
        <Value>value2</Value>
    </MyEntry>
</MyMap>

我见过@JacksonXmlElementWrapper，但它似乎不允许命名实体的XML元素，而是命名Map的XML元素。我不知道这是一个bug还是预期的行为。但我希望有办法解决。
我使用的演示代码以防有人想复制

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.dataformat.xml.annotation.*;
import lombok.*;
import org.junit.jupiter.api.Test;

import java.util.Map;

import static org.junit.jupiter.api.Assertions.*;

public class ReproductionTest {

    private static final String XML = """
<MyRoot>
    <MyMap>
        <MyEntry><Key>key1</Key><Value>value1</Value></MyEntry>
        <MyEntry><Key>key2</Key><Value>value2</Value></MyEntry>
        <!--33Key3>Not an option since I don't control keys to have valid XML names</33Key3-->
    </MyMap>
    <MyString>abc</MyString>
</MyRoot>""";

    @NoArgsConstructor
    @Getter
    @Setter
    @ToString
    static class MyRoot {
        @JacksonXmlProperty(localName = "MyMap")
        // With the next line uncommented, the following exception is thrown:
        // UnrecognizedPropertyException: Unrecognized field "MyMap"...
        // not marked as ignorable (2 known properties: "MyString", "MyEntry"])
        //@JacksonXmlElementWrapper(localName = "MyEntry")
        Map<String, String> myMap;
        @JacksonXmlProperty(localName = "MyString")
        String myString;
    }

    @Test
    public void reproducesDeserializationIssue() throws JsonProcessingException {
        XmlMapper xmlMapper = new XmlMapper();
        MyRoot myRoot = xmlMapper.readValue(XML, MyRoot.class);
        xmlMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, true); // re-enforcing default
        assertEquals("abc", myRoot.getMyString());          // passes
        assertEquals(1, myRoot.getMyMap().size());          // passes
        assertNotNull(myRoot.getMyMap().get("MyEntry"));    // passes, unexpectedly
        assertEquals("", myRoot.getMyMap().get("MyEntry")); // passes, unexpectedly
        assertNull(myRoot.getMyMap().get("key1"));          // passes, unexpectedly
        assertNull(myRoot.getMyMap().get("key2"));          // passes, unexpectedly
        System.out.println(xmlMapper.writeValueAsString(myRoot));
        // Prints <MyRoot><myMap><myItem></myItem></myMap><myString>abc</myString></MyRoot>
    }
}

P.S.在这一点上，我不能控制XML模式，也不能输出POJO。但我可以控制XmlMapper配置。因此，我的理解是，我的选项仅限于MixIns和自定义反序列化器。但希望有更简单的解决办法。