Default values for new properties

Im using ObjectBox in a pet android project written in Kotlin.. I have a data class encoded as such (example):

@Entity data class Foo(var name:String, var description: String) {
    constructor() : this("", "") // parameter-less constructor
    @Id var id: Long = 0L
    // other stuff
}

Database already existed on the device.. I added an additional property to the Foo class (not in the data constructor):

@Entity data class Foo(var name:String, var description: String) {
    constructor() : this("", "") // parameter-less constructor
    @Id var id: Long = 0L
    var bar: String = ""
    // other stuff
}

defaulted, non-null object bar.. however when pulling existing records from the stored box, that value bar appears to be null.. I would expect it to be a blank string (default for the parameter); is the violation of not-null guarantee coming from the Java interop?

I fixed the issue by nuking the database; afterwords the entity created and stored is not-null.. But this brings up any possible future updates that may violate this.

Is there a "database upgrade" method for updating already stored objects between versions, adding default values to new properties, or am I resigned to make anything added to an existing model be nullable (and handle it as such)?

该 issue 提供了一个 Kotlin Foo 实体，并描述了 ObjectBox 数据库中的现有记录，但没有指出任何 repository 文件或测试。首先，在向 Foo 添加 bar 后复现其行为，然后检查实体迁移和现有记录加载路径。完成的标准是确定新的非空属性如何为已存储的记录获取默认值，并为未来的升级提供覆盖或文档。