string和StringProperty之间不兼容的类型

Question

我正在学习很多关于如何填充JFXTreeTableView的教程

我写了完全相同的代码，导入相同的软件包，我得到了这种类型的错误

Error:(137, 52) java: incompatible types: com.sun.org.apache.xpath.internal.operations.String cannot be converted to java.lang.String

有代码

class User extends RecursiveTreeObject<User> {

    StringProperty userName;
    StringProperty age;
    StringProperty department;

    public User(String department, String age, String userName) {
        this.department = new SimpleStringProperty(department); //departement is underlined 
        this.userName = new SimpleStringProperty(userName); //userName is underlined
        this.age = new SimpleStringProperty(age); // age is underlined
    }