@ApiModel添加实体类不生效

<!-- https://mvnrepository.com/artifact/io.springfox/springfox-swagger2 -->
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger2</artifactId>
    <version>2.9.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/io.springfox/springfox-swagger-ui -->
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger-ui</artifactId>
    <version>2.9.2</version>
</dependency>

@ApiModel("用户实体类")
public class User {
    @ApiModelProperty("用户名")
    private String username;
    @ApiModelProperty("密码")
    private String password;
}

@PostMapping("/user")
public User user() {
    return new User();
}

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
@ApiModel("用户实体类")
public class User {
    @ApiModelProperty("用户名")
    private String username;
    @ApiModelProperty("密码")
    private String password;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }    
}