QueryBuilder's notEqual doesn't return objects where that field is null

It's in the title, but a concrete example would be. Say we have a model with a String field called field. We have two objects in the database, one of them has field set to an empty String and another one has it set to null. The following query returns the one with the empty field but not the one with null:

box.query().notEqual(Model_.field, "hello world").build().find()

Basic info (please complete the following information):

• ObjectBox version: latest (2.7.1)
• Reproducibility: always
• Device: any
• OS: any

Expected behavior

An object with a particular field being null should match a notEqual which contains any non-null value, instead it doesn't.

Code

        store = MyObjectBox.builder().androidContext(this).buildDefault()
        val box = store.boxFor(Model::class.java)
        box.removeAll()
        Log.d("TEST_LOG", "putting null with id: " + box.put(Model(0, null)))
        Log.d("TEST_LOG", "putting empty with id: " + box.put(Model(0, "")))
        val logString = models.map { it.id }.sorted().joinToString()
        Log.d("TEST_LOG", "models: $logString")

Where Model has a single String field called field

The above code clearly logs only the model with the empty field being returned but not the one with the null value for field. Maybe I'm misunderstanding something but this is a very unintuitive definition of notEqual and nothing in the docs seems to indicate it would behave this way.

从 QueryBuilder.notEqual 开始，跟踪 box.query().notEqual(Model_.field, "hello world").build().find() 使用的查询路径，重点关注如何处理字段值为 null 的情况。根据 Model 示例添加一个回归用例，并验证查询同时返回空字符串对象和 null 对象。