libgdx-bullet btGImpactMeshShape doesn't work for Rigidbody

Question

I am new to bullet physics and already facing annoying problem with shapes,...I have this java class that extends ModelInstance:

public class CustomModel extends ModelInstance implements Disposable {
    RigidBodyInfo rigidBodyInfo;
    btRigidBody rigidBody;
    //btBvhTriangleMeshShape shape;
    btCollisionShape shape;
    btTriangleIndexVertexArray vertexArray;
    public CustomModel(Model model,btDynamicsWorld world,float mass){
        super(model);
        vertexArray = new btTriangleIndexVertexArray(model.meshParts);
        if(mass==0){
        shape=new btBvhTriangleMeshShape(vertexArray,true);
        } else{
            shape=new btGImpactMeshShape(vertexArray);
            shape.setLocalScaling(new Vector3(1,1,1));
            shape.setMargin(0);
            ((btGImpactMeshShape)shape).updateBound();
            }
        rigidBodyInfo=new RigidBodyInfo(mass,shape);
        rigidBody = new btRigidBody(rigidBodyInfo);
        rigidBody.setRestitution(0);
        rigidBody.setMotionState(new GameMotionState(this));
        world.addRigidBody(rigidBody);
        //rigidBody.setActivationState(Collision.DISABLE_DEACTIVATION);
        
    }
    
    public btRigidBody getRigidBody(){
        return rigidBody;
    }
    
    public void setTranslation(Vector3 vector3){
        transform.setTranslation(vector3);
        rigidBody.setWorldTransform(transform);
        rigidBody.setLinearVelocity(new Vector3());
        rigidBody.setActivationState(Collision.ACTIVE_TAG);
    }
    
    public void setTranslation(float x,float y,float z){
        transform.setTranslation(x,y,z);
        rigidBody.setWorldTransform(transform);
        rigidBody.setLinearVelocity(new Vector3());
        rigidBody.setActivationState(Collision.ACTIVE_TAG);
    }
    
    @Override
    public void dispose() {
        rigidBody.dispose();
        rigidBodyInfo.dispose();
        if(vertexArray!=null)
            vertexArray.dispose();
        shape.dispose();
    }
}

the problem is happening when I add two Boxes using ModelBuilder.createBox, the two boxes doesn't collide with each other.. i have read that btBvhTriangleMeshShape is for only static bodies, also i have tried Bullet.obtainStaticNodeShape(...), and it doesn't work for me. how i create the Model :

Model cubeModel = new ModelBuilder().createBox(0.25f,0.25f,0.25f,material,VertexAttributes.Usage.Position|VertexAttributes.Usage.Normal|VertexAttributes.Usage.TextureCoordinates);

        modelInstance = new CustomModel(cubeModel,world,0);

        cube = new CustomModel(cubeModel,world,1);

        cube.setTranslation(0f,10,0f);

then render it normally .. RigidBodyInfo class :

public class RigidBodyInfo extends btRigidBody.btRigidBodyConstructionInfo {
    public static Vector3 tempV=new Vector3();
    public RigidBodyInfo(float mass,btCollisionShape shape){
        super(mass,null,shape,calc(mass,shape));
    }
    
    public static Vector3 calc(float mass,btCollisionShape shape){
        shape.calculateLocalInertia(mass,tempV);
        return tempV;
    }
    
    @Override
    public void dispose() {
        super.dispose();
    }
}

i have have tried: Bullet.obtainStaticNodeShape() and it works good with btBoxShape but I don't need it ...