ObjectBox和Ktor

Question

是否可以在Ktor的应用程序中使用ObjectBox？我有以下 build.gradle 文件：

buildscript {
    // Consider moving these values to `gradle.properties`
    ext.kotlin_version = '1.2.70'
    ext.ktor_version = '0.9.4'
    ext.appengine_version = '1.9.60'
    ext.appengine_plugin_version = '1.3.4'
    ext.objectbox_version = '2.1.0'

    repositories {
        jcenter()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "com.google.cloud.tools:appengine-gradle-plugin:$appengine_plugin_version"
        classpath "io.objectbox:objectbox-gradle-plugin:$objectbox_version"
    }
}

apply plugin: 'kotlin'
apply plugin: 'war'
apply plugin: 'com.google.cloud.tools.appengine'
// to enable gradle in IntelliJ IDEA
apply plugin: 'idea'
apply plugin: 'java'
apply plugin: 'kotlin-kapt'
apply plugin: 'io.objectbox'

sourceSets {
    main.kotlin.srcDirs = [ 'src/main/kotlin' ]
}

repositories {
    jcenter()
    maven { url "https://kotlin.bintray.com/ktor" }
    maven { url "https://dl.bintray.com/kotlin/exposed" }
}

dependencies {
    compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
    compile "io.ktor:ktor-server-servlet:$ktor_version"
    compile "io.ktor:ktor-html-builder:$ktor_version"
    compile "io.ktor:ktor-gson:$ktor_version"
    compile "io.ktor:ktor-freemarker:$ktor_version"

    compile 'org.jetbrains.exposed:exposed:0.8.5'
    compile group: 'mysql', name: 'mysql-connector-java', version: '8.0.12'

    providedCompile "com.google.appengine:appengine:$appengine_version"
}

kotlin.experimental.coroutines = 'enable'

task run(dependsOn: appengineRun)

起初，项目运行成功。那时我有模型课：

class User()

但是当我在类中添加了两个注释-@Entity包中的@Id和io.objectbox.annotation时：

@Entity
class User(@Id val id: Long)

发生错误：java.lang.reflect.UndeclaredThrowableException。尽管有错误，ObjectBox仍使用MyObjectBox生成了代码：

此错误的原因是什么？而且我知道大多数ObjectBox被认为是移动设备的数据库。那么是否有可能在与Ktor一起使用的应用程序中将ObjectBox用作数据库？