升级JDK11与enunciate插件后，泛型类编译失败求助

问题场景 #

维护的遗留项目从Java 8 + Enunciate Maven插件2.13.0升级到JDK 11 + Enunciate 2.15.1后，执行docs goal时出现Java JSON客户端类编译失败。父POM中jax-rs-api profile配置如下：

<profile>
    <id>jax-rs-api</id>
    <dependencies>
        <dependency>
            <groupId>com.webcohesion.enunciate</groupId>
            <artifactId>enunciate-core-annotations</artifactId>
            <version>${enunciate-maven-plugin.version}</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>com.webcohesion.enunciate</groupId>
                <artifactId>enunciate-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>docs</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</profile>

涉及的抽象DTO类：

public abstract class IdentityView<T> {

    private String accountId;
    private T profile;
    private ConfigurationView configuration;

    // setters & getters
}

编译错误显示生成的客户端代码中泛型T被错误替换为?，导致语法错误：

C:\...\my-project\target\enunciate\java-json-client\src\com\my-project\data\view\IdentityView.java:21: error: illegal start of type
  private ? _profile;
          ^
C:\...\my-project\target\enunciate\java-json-client\src\com\my-project\data\view\IdentityView.java:21: error: <identifier> expected
  private ? _profile;
                    ^
C:\...\my-project\target\enunciate\java-json-client\src\com\my-project\data\view\IdentityView.java:45: error: illegal start of type
  public ? getProfile() {
         ^
C:\...\my-project\target\enunciate\java-json-client\src\com\my-project\data\view\IdentityView.java:45: error: invalid method declaration; return type required
  public ? getProfile() {
           ^
C:\...\my-project\target\enunciate\java-json-client\src\com\my-project\data\view\IdentityView.java:53: error: illegal start of type
  public void setProfile(? _profile) {

解决思路 #

• 显式指定泛型边界或添加Enunciate注解：Enunciate对无边界泛型的类型推断可能存在问题，给T添加边界约束（如T extends BaseProfile），或者添加Enunciate的@JsonTypeInfo注解明确类型信息：

  import com.webcohesion.enunciate.metadata.json.JsonTypeInfo;
  
  @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@type")
  public abstract class IdentityView<T> {
      // 原有代码
  }
  

• 调整Enunciate插件配置：如果不需要Java JSON客户端，直接禁用该模块：

  <plugin>
      <groupId>com.webcohesion.enunciate</groupId>
      <artifactId>enunciate-maven-plugin</artifactId>
      <executions>
          <execution>
              <goals>
                  <goal>docs</goal>
              </goals>
          </execution>
      </executions>
      <configuration>
          <modules>
              <java-json-client>
                  <disabled>true</disabled>
              </java-json-client>
          </modules>
      </configuration>
  </plugin>
  

  若需保留客户端，可尝试配置泛型处理参数，比如指定genericTypes来明确泛型映射。

• 升级Enunciate版本：2.15.x版本可能存在泛型处理的bug，升级到最新稳定版本（如2.18.0+），官方可能已修复此类问题。

• 配置JDK编译兼容参数：确保Enunciate使用JDK 11的编译参数，在插件配置中添加：

  <plugin>
      <groupId>com.webcohesion.enunciate</groupId>
      <artifactId>enunciate-maven-plugin</artifactId>
      <executions>
          <execution>
              <goals>
                  <goal>docs</goal>
              </goals>
          </execution>
      </executions>
      <configuration>
          <compileArgs>
              <arg>-source</arg>
              <arg>11</arg>
              <arg>-target</arg>
              <arg>11</arg>
          </compileArgs>
      </configuration>
  </plugin>
  

• 处理抽象类的泛型识别：确保IdentityView的子类被Enunciate扫描到，或者给抽象类添加泛型实例化的提示，帮助Enunciate正确识别泛型类型。

内容的提问来源于stack exchange，提问作者ChambreNoire