我目前正在为azuresdkforjava修复一个bug，当我试图将一些json反序列化到一个带有可选的类中时，我得到了一个invliddefinitionexception。我做错什么了？我的pom.xml中有以下依赖项：

<dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.11.2</version>
    </dependency>

    <dependency>
      <groupId>com.fasterxml.jackson.datatype</groupId>
      <artifactId>jackson-datatype-jdk8</artifactId>
      <version>2.11.2</version>
    </dependency>

下面是执行反序列化的代码：

final ObjectMapper objectMapper = JacksonObjectMapperFactory.getInstance();
        objectMapper.registerModule(new Jdk8Module());
        UserGroups groupsFromJson = objectMapper.readValue(responseInJson, UserGroups.class);

public final class JacksonObjectMapperFactory {

    private JacksonObjectMapperFactory() {
    }

    public static ObjectMapper getInstance() {
        return SingletonHelper.INSTANCE;
    }

    private static class SingletonHelper {
        private static final ObjectMapper INSTANCE = new ObjectMapper();
    }
}

下面是用于反序列化的Map类：

import java.util.List;
import java.util.Objects;
import java.util.Optional;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonProperty;

@JsonIgnoreProperties(ignoreUnknown = true)
public class UserGroups {

    @JsonProperty("odata.nextLink")
    private Optional<String> odataNextLink;

    @JsonProperty("value")
    private List<UserGroup> value;

    public UserGroups(Optional<String> odataNextLink, List<UserGroup> value) {
        this.odataNextLink = odataNextLink;
        this.value = value;
    }

    public Optional<String> getOdataNextLink() {
        return odataNextLink;
    }

    public List<UserGroup> getValue() {
        return value;
    }
}

下面是usergroup类：

import java.io.Serializable;
import java.util.Objects;

import com.fasterxml.jackson.annotation.JsonAlias;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonProperty;

@JsonIgnoreProperties(ignoreUnknown = true)
public class UserGroup implements Serializable {
    private static final long serialVersionUID = 9064197572478554735L;

    @JsonProperty("objectId")
    @JsonAlias("id")
    private String objectID;

    @JsonProperty("objectType")
    @JsonAlias("@odata.type")
    private String objectType;

    @JsonProperty("displayName")
    private String displayName;

    public UserGroup(String objectID, String objectType, String displayName) {
        this.objectID = objectID;
        this.objectType = objectType;
        this.displayName = displayName;
    }

    public String getDisplayName() {
        return displayName;
    }

    public String getObjectType() {
        return objectType;
    }

    public String getObjectID() {
        return objectID;
    }

    @Override
    public boolean equals(Object o) {
        if (o == this) {
            return true;
        }
        if (!(o instanceof UserGroup)) {
            return false;
        }
        final UserGroup group = (UserGroup) o;
        return this.getDisplayName().equals(group.getDisplayName())
                && this.getObjectID().equals(group.getObjectID())
                && this.getObjectType().equals(group.getObjectType());
    }

    @Override
    public int hashCode() {
        return Objects.hash(objectID, objectType, displayName);
    }
}

以下是运行测试时出现的错误：

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: 
Cannot construct instance of `com.microsoft.azure.spring.autoconfigure.aad.UserGroups` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)
 at [Source: (String)"{"odata.metadata":"https://graph.windows.net/myorganization/$metadata#directoryObjects","value":[{"odata.type":"Microsoft.DirectoryServices.Group","objectType":"Group","objectId":"12345678-7baf-48ce-96f4-a2d60c26391e","deletionTimestamp":null,"description":"this is group1","dirSyncEnabled":true,"displayName":"group1","lastDirSyncTime":"2017-08-02T12:54:37Z","mail":null,"mailNickname":"something","mailEnabled":false,"onPremisesDomainName":null,"onPremisesNetBiosName":null,"onPremisesSamAccountNam"[truncated 1554 chars]; line: 1, column: 2]
    at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
    at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1615)

这是我想反序列化的json示例：

{
   "odata.metadata":"https://graph.windows.net/myorganization/$metadata#directoryObjects",
   "odata.nextLink":"directoryObjects/$/Microsoft.DirectoryServices.User/userId/memberOf?$skiptoken=X'XXXXXXXX'",
   "value":[
      {
         "odata.type":"Microsoft.DirectoryServices.Group",
         "objectType":"Group",
         "objectId":"12345678-7baf-48ce-96f4-a2d60c26391e",
         "deletionTimestamp":null,
         "description":"this is group1",
         "dirSyncEnabled":true,
         ...
      }
   ]
}

我不是很有经验的Jackson，任何帮助是非常感谢。谢谢你读了这么远！