我加的属性有点多，可以根据你的实际情况去掉部分代码。
其中，lft/rgt是专门优化Tree查询的，可以不使用递归，一次查找，就能拿到整棵树。
总之，偏实战的代码。

open class Tree (id: Long,
                 parentId: Long? = null,
                lft: Int? = null, // left position
                rgt: Int? = null, // right position
                depth: Int? = null, // level, root node level = 1
                leaf: Boolean? = null, / / is the leaf node (front-end get this property's value, then can use to show whether to extension the menu)
                teamTotal: Int? = null, // number of teams (all subordinates)
                childrenTotal: Int? = null) // The number of immediate subordinates

enum class Position {
     LEFT, RIGHT, DOWN
}

data class User(
        // inherits from UserDetails
        private val username: String,
        private val password: String,
        private val isEnabled: Boolean, //Disabled account can not log in
        private val isCredentialsNonExpired: Boolean, //credential can be expired,eg. Change the password every three months
        private val isAccountNonExpired: Boolean, //eg. Demo account（guest） can only be online  24 hours
        private val isAccountNonLocked: Boolean, //eg. Users who malicious attack system,lock their account for one year
        private val authorities: Set<GrantedAuthority>, 

        // inherits from Tree.If the user is not a tree structure, can be ignored
        val id: Long,
        val parentId: Long? = null, 
        val lft: Int? = null, // preorder tree traversal algorithm
        val rgt: Int? = null, // preorder tree traversal algorithm
        val depth: Int? = null, // or levels
        val isLeaf: Boolean? = null, 
        val teamTotal: Int? = null, // The number of all subordinates
        val childrenTotal: Int? = null, //The number of all directly under the subordinate

        //Custom attributes
        val tenantId: Long, //We are the platform + tenant model
        val role: Set<Role>, // TENANT, SUBACCOUNT, DEFAULT_GROUP, MEMBER, GUEST
        val platform: Platform, // PC, IOS, ANDROID, WAP, INTERNAL
        val deviceToken: String? = null, //or machine code
        val ip: InetAddress //Inet4Address or Inet6Address
) : UserDetails, Tree(id, parentId) {
    override fun getUsername(): String = username
    override fun getPassword(): String = password
    override fun isEnabled(): Boolean = isEnabled
    override fun isCredentialsNonExpired(): Boolean = isCredentialsNonExpired
    override fun isAccountNonExpired(): Boolean = isAccountNonExpired
    override fun isAccountNonLocked(): Boolean = isAccountNonLocked
    override fun getAuthorities(): Set<out GrantedAuthority> = authorities
}