flutter release apk crash on bixolon sdk call from plugin

I'm trying to use Bixolon SDK in my flutter plugin, in debug mode every thing is good and working in perfection . But, when I go on release mode it's crash, application is close and the following error displayed :

    F/example.alsahi(21380): thread.cc:2155] No pending exception expected: java.lang.ClassNotFoundException: Didn't find class "com.bixolon.commonlib.emul.EscPosEmul" on path: DexPathList[[zip file "/data/app/com.example.alsahil-SQ9CSxBQ66--Q9wfyJTfmQ==/base.apk"],nativeLibraryDirectories=[/data/app/com.example.alsahil-SQ9CSxBQ66--Q9wfyJTfmQ==/lib/arm, /data/app/com.example.alsahil-SQ9CSxBQ66--Q9wfyJTfmQ==/base.apk!/lib/armeabi-v7a, /system/lib, /system/vendor/lib]]
F/example.alsahi(21380): thread.cc:2155]   at java.lang.Class dalvik.system.BaseDexClassLoader.findClass(java.lang.String) (BaseDexClassLoader.java:134)
F/example.alsahi(21380): thread.cc:2155]   at java.lang.Class java.lang.ClassLoader.loadClass(java.lang.String, boolean) (ClassLoader.java:379)    
F/example.alsahi(21380): thread.cc:2155]   at java.lang.Class java.lang.ClassLoader.loadClass(java.lang.String) (ClassLoader.java:312)
F/example.alsahi(21380): thread.cc:2155]   at java.lang.String java.lang.Runtime.nativeLoad(java.lang.String, java.lang.ClassLoader) (Runtime.java:-2)
F/example.alsahi(21380): thread.cc:2155]   at void java.lang.Runtime.loadLibrary0(java.lang.ClassLoader, java.lang.String) (Runtime.java:1014)     
F/example.alsahi(21380): thread.cc:2155]   at void java.lang.System.loadLibrary(java.lang.String) (System.java:1669)
F/example.alsahi(21380): thread.cc:2155]   at void j.d.<clinit>() (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void n.a.a.b.<init>(android.content.Context) (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void n.a.a.c.a(byte[], java.lang.String, java.lang.String, android.content.Context) (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void n.a.a.a.h(i.a.c.a.i, i.a.c.a.j$d) (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void i.a.c.a.j$a.a(java.nio.ByteBuffer, i.a.c.a.b$b) (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void io.flutter.embedding.engine.f.c.i(io.flutter.embedding.engine.f.c$d, java.nio.ByteBuffer, int) (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void io.flutter.embedding.engine.f.c.j(java.lang.String, io.flutter.embedding.engine.f.c$d, java.nio.ByteBuffer, int, long) (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void io.flutter.embedding.engine.f.c.k(java.lang.String, io.flutter.embedding.engine.f.c$d, java.nio.ByteBuffer, int, long) (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void io.flutter.embedding.engine.f.a.run() (:-1)
F/example.alsahi(21380): thread.cc:2155]   at void android.os.Handler.handleCallback(android.os.Message) (Handler.java:873)
F/example.alsahi(21380): thread.cc:2155]   at void android.os.Handler.dispatchMessage(android.os.Message) (Handler.java:99)
F/example.alsahi(21380): thread.cc:2155]   at void android.os.Looper.loop() (Looper.java:214)
F/example.alsahi(21380): thread.cc:2155]   at void android.app.ActivityThread.main(java.lang.String[]) (ActivityThread.java:7156)
F/example.alsahi(21380): thread.cc:2155]   at java.lang.Object java.lang.reflect.Method.invoke(java.lang.Object, java.lang.Object[]) (Method.java:-2)
F/example.alsahi(21380): thread.cc:2155]   at void com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run() (RuntimeInit.java:494)
F/example.alsahi(21380): thread.cc:2155]   at void com.android.internal.os.ZygoteInit.main(java.lang.String[]) (ZygoteInit.java:975)
F/example.alsahi(21380): thread.cc:2155]
F/example.alsahi(21380): runtime.cc:577] Runtime aborting...
F/example.alsahi(21380): runtime.cc:577] Dumping all threads without appropriate locks held: thread list lock

and this is my app level build gradle :

compileSdkVersion flutter.compileSdkVersion

compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}

defaultConfig {
    // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
    applicationId "com.example.alsahil"
    minSdkVersion 21
    targetSdkVersion flutter.targetSdkVersion
    versionCode flutterVersionCode.toInteger()
    versionName flutterVersionName
    multiDexEnabled true
}
signingConfigs {
    release {
        keyAlias keystoreProperties['keyAlias']
        keyPassword keystoreProperties['keyPassword']
        storeFile keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
        storePassword keystoreProperties['storePassword']
    }
}

buildTypes {
    release {
        signingConfig signingConfigs.release
    }
}

and here is my AndroidManifest.xml

  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.alsahil">
    <uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
    <uses-permission android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.BLUETOOTH"/>
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

photo that show the plugin files

any help is appreciated ..