条件API不执行查询

Question

我有一个DAO，可以过滤列表。

    public List<User> filterUser(UserView userView) {
    List<User> userList;
    Long officeId = userView.officeId;
    String firstName = userView.firstName;
    String secondName = userView.secondName;
    String middleName = userView.middleName;
    String position = userView.position;
    String docCode = userView.docCode;
    String citizenshipCode = userView.citizenshipCode;

    CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
    CriteriaQuery<User> userQuery = criteriaBuilder.createQuery(User.class);
    Root<User> userRoot = userQuery.from(User.class);
    Join<User, Document> docJoin = userRoot.join("document");
    Join<Document, DocType> docTypeJoin = docJoin.join("docType");
    Join<Document, Country> countryJoin = docJoin.join("country");

    userQuery.select(userRoot);
    userQuery.where(criteriaBuilder.equal(userRoot.get("office"), officeId));

    if (firstName != null) {
        userQuery.where(criteriaBuilder.equal(userRoot.get("firstName"), firstName));
    }
    if (secondName != null) {
        userQuery.where(criteriaBuilder.equal(userRoot.get("secondName"), secondName));
    }
    if (middleName != null) {
        userQuery.where(criteriaBuilder.equal(userRoot.get("middleName"), middleName));
    }
    if (position != null) {
        userQuery.where(criteriaBuilder.equal(userRoot.get("position"), position));
    }

    if (docCode != null) {
        userQuery.where(criteriaBuilder.equal(docTypeJoin.get("code"), docCode));
    }

    if (citizenshipCode != null) {
        userQuery.where(criteriaBuilder.equal(countryJoin.get("code"), citizenshipCode));
    }

    userList = em.createQuery(userQuery).getResultList();
    return userList;
}

如果我请求字段officeId，firstName，secondName等，则一切正常。

docCode和citizenshipCode的问题。例如，当我发送officeId和docCode时，过滤器仅适用于docCode，而不适用于officeId。

如果我在这样的地方更改行：

userQuery.where(criteriaBuilder.equal(docTypeJoin.get("code"), docCode));

及之后

  userQuery.where(criteriaBuilder.equal(userRoot.get("office"), officeId));

我的列表中只有officeId，而没有docCode。