Android4.4以前版本dex拆分

Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.demo.ApplicationUser" on path: DexPathList[[zip file "/data/app/comexample.demo-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.demo-1, /vendor/lib, /system/lib]]
                                                     at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
                                                     at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
                                                     at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
                                                     at android.app.Instrumentation.newApplication(Instrumentation.java:975)
                                                     at android.app.LoadedApk.makeApplication(LoadedApk.java:502)
                                                     at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4311) 
                                                     at android.app.ActivityThread.access$1500(ActivityThread.java:139) 
                                                     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1260) 
                                                     at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                     at android.os.Looper.loop(Looper.java:136) 
                                                     at android.app.ActivityThread.main(ActivityThread.java:5011) 
                                                     at java.lang.reflect.Method.invokeNative(Native Method) 
                                                     at java.lang.reflect.Method.invoke(Method.java:515) 
                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:832) 
                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:648) 
                                                     at dalvik.system.NativeStart.main(Native Method) 
com.example.demo.ApplicationUser 是在classes2.dex，怎么把ApplicationUser 放到classes.dex中
使用这种方法没有作用afterEvaluate {
        tasks.matching {
            it.name.startsWith('dex')
        }.each { dx ->
            def listMain = project.rootDir.absolutePath+'/app/manifest_keep.txt'
            if (dx.additionalParameters == null) {
                dx.additionalParameters = []
            }
            //改变dex方法数上线为50000，超过后进行拆分
            dx.additionalParameters += '--set-max-idx-number=50000'
            //方法数越界时则生成多个dex文件
            dx.additionalParameters += '--multi-dex'
            //maindexlist.txt文件为主dex中的类型配置文件
            dx.additionalParameters += '--main-dex-list=' + listMain
            //-main-dex-list指定的所有class会打包到主dex中
            dx.additionalParameters += '--minimal-main-dex'
        }
    }manifest_keep.txt文件设置为
com/example/demo/ApplicationUser.class
android/support/multidex/MultiDex.class
android/support/multidex/MultiDexApplication.class
android/support/multidex/MultiDexExtractor.class
android/support/multidex/MultiDexExtractor$1.class
android/support/multidex/MultiDex$4.class
android/support/multidex/MultiDex$14.class
android/support/multidex/MultiDex$19.class
android/support/multidex/ZipUtil.class
android/support/multidex/ZipUtil$CentralDirectory.class请大神帮忙解决一下，给个建议！！！