Cannot find the setter for attribute in Data binding

I am using LiveData, DataBinding, and Kotlin in my application.

I defined a Binding Adapter for a RecyclerView like this:

class MainListBindings {

private val TAG = "TasksListBindings"

companion object {

@JvmStatic
@SuppressWarnings("unchecked")
@BindingAdapter("main_items")
fun setItems(recyclerView: RecyclerView, items: MutableLiveData<List<Homeitem>>? = null) {

val adapter: RecyclerMainAdapter = recyclerView.adapter as RecyclerMainAdapter
//prevent use of null list
items?.let {

adapter.swapData(items)
}
}

}
}

and my reyclerView in XML assigned to this bindingAdapter like this:

<android.support.v7.widget.RecyclerView
android:id="@+id/main_recycler"
app:main_items="@{viewmodel.items}"
android:layout_width="match_parent"
android:layout_height="match_parent"/>

And in my ViewModel, I used

val items = MutableLiveData<List<Homeitem>>()

to create the list.

But I am getting this error at building Application:

Found data binding errors.
****/ data binding error ****msg:Cannot find the setter for attribute 'app:main_items' with parameter type android.arch.lifecycle.MutableLiveData<java.util.List<project.data.pojo.Homeitem>> on android.support.v7.widget.RecyclerView. file:/home/user/Yara/bazinama_mag/bazinama/app/src/main/res/layout/fragment_main.xml loc:22:24 - 22:38 ****\ data binding error ****

**Binding Adapter**

@JvmStatic
@BindingAdapter("main_items")
fun setItems(recyclerView: RecyclerView, items: MutableLiveData<List<String>>) {

}

**Model**


class User : ViewModel(){
lateinit var list: MutableLiveData<List<String>>
}

**Bind Data**

val items = ViewModelProviders.of(this@FragmentName)
.get(RecyclerViewHelper.User::class.java)
mBinding!!.user = items

**Layout**

<layout>
<data>
<variable
name="user"
type="com.XXX.view.recylerview.RecyclerViewHelper.User" />
</data>

<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<android.support.v7.widget.RecyclerView
android:id="@+id/helper_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layoutManager="android.support.v7.widget.LinearLayoutManager"
app:main_items="@{user.list}" />

</RelativeLayout>

</layout>

There might be different reasons for this error but in my case, the problem raised up because I didn't add `apply plugin: 'kotlin-kapt'` And `apply plugin: 'kotlin-android-extensions'` in my `Gradle`.

After adding these plugins you have to replaced your `annotationProcessors` with `kapt`.

After that, every thing might be going well.

Check if you have any space after the `@BindingAdapter` value like this:
```
@BindingAdapter("sleepDurationFormatted ")
^
|
here
```
Took me 2hours to find out.