Function Java_com_stateset_embedded_Carts_nativeAddItem 

#[unsafe(no_mangle)]
pub extern "system" fn Java_com_stateset_embedded_Carts_nativeAddItem<'local>(
    env: JNIEnv<'local>,
    _class: JClass<'local>,
    ptr: jlong,
    cart_id: JString<'local>,
    sku: JString<'local>,
    name: JString<'local>,
    quantity: jint,
    unit_price: jdouble,
) -> JObject<'local>