<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <EditText
        android:id="@+id/voice_edittext"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:hint="Add answer here"
        />

    <ImageButton
        android:id="@+id/microphone_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_mic_black_24dp"
        />
    <ImageButton
        android:id="@+id/delete_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_cancel_black_24dp"
        android:visibility="gone"
        />
    </LinearLayout>

<com.sunilson.quizcreator.presentation.views.EditTextWithVoiceInput
                android:id="@+id/form_question"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="10dp"
                android:layout_marginTop="10dp"
                app:editTextValue="@={viewModel.observableText}"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintTop_toTopOf="parent" />

@BindingAdapter("editTextValueAttrChanged")
fun setListener(editTextWithVoiceInput: EditTextWithVoiceInput, listener: InverseBindingListener) {
    editTextWithVoiceInput.voice_edittext.addTextChangedListener(object : TextWatcher {
        override fun afterTextChanged(p0: Editable?) {
            listener.onChange()
        }

        override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
        override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
    })
}

@BindingAdapter("editTextValue")
fun setTextValue(editTextWithVoiceInput: EditTextWithVoiceInput, value: String?) {
    if (value != editTextWithVoiceInput.voice_edittext.text.toString()) editTextWithVoiceInput.voice_edittext.setText(value)
}

@InverseBindingAdapter(attribute = "editTextValue")
fun getTextValue(editTextWithVoiceInput: EditTextWithVoiceInput): String? {
    return editTextWithVoiceInput.voice_edittext.text.toString()
}

class EditTextWithVoiceInput(context: Context, attributeSet: AttributeSet) : LinearLayout(context, attributeSet) {

    init {
        val inflater = context?.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
        val view = inflater.inflate(R.layout.voice_edittext, this, true)

        view.microphone_button.setOnTouchListener { p0, p1 ->
            ...
        }
    }
}

java.lang.NullPointerException: Attempt to invoke virtual method 'void <MY_PACKAGE_NAME>.EditTextWithVoiceInput.setTag(java.lang.Object)' on a null object reference