Realm 2.1.1 + kotlin 1.1.3　の環境です。

maigrationの過程で必ず「RealmMigrationNeededException: Field count is more than expected」の例外が発生します。

migration前

public open class TestObject():RealmObject(){
@PrimaryKey
open var name:String = ""
open var age:Int = 0
}

migration後

public open class TestObject():RealmObject(){
@PrimaryKey
open var name:String = ""
open var age:Int = 0
open var hogehoge:String = ""//追加
}

migrationObject

class MyMigration:RealmMigration{

override fun migrate(realm: DynamicRealm?, oldVersion: Long, newVersion: Long) {
    Log.i("","oldVersion $oldVersion newVersion $newVersion")
    var oldVersion = oldVersion

    val schema = realm!!.schema

    if(oldVersion == 0L){
        var a = schema.get("TestObject")
        a.addField("hogehoge", String::class.java, FieldAttribute.REQUIRED)
        oldVersion++
    }
}
}

appllicationのmaigration部分

Realm.init(this)
    val builder = RealmConfiguration.Builder()
    builder.schemaVersion(1L).migration(MyMigration())
    val config = builder.build()
    Realm.setDefaultConfiguration(config)

error発生箇所
MainActivity

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    Fabric.with(this,  Crashlytics(),  CrashlyticsNdk());
    setContentView(R.layout.activity_start)

    Log.i("mainActivity","startMainActivity")
    val realm = Realm.getDefaultInstance()//エラー発生

エラー内容

Caused by: io.realm.exceptions.RealmMigrationNeededException: Field count is more than expected - expected 2 but was 3
at io.realm.TestObjectRealmProxy.validateTable(TestObjectRealmProxy.java:182)
at io.realm.DefaultRealmModuleMediator.validateTable(DefaultRealmModuleMediator.java:186)
at io.realm.Realm.initializeRealm(Realm.java:344)
at io.realm.Realm.createAndValidate(Realm.java:301)
at io.realm.Realm.createInstance(Realm.java:280)
at io.realm.RealmCache.createRealmOrGetFromCache(RealmCache.java:143)
at io.realm.Realm.getDefaultInstance(Realm.java:211)
at jp.co.futaba_d.bluebear.MainActivity.onCreate(MainActivity.kt:103)

オブジェクトの種類を問わず必ず発生します。
どなたか、ご教授願えれば幸いです。