Similar to `by`, but for other methods than get/set methods - kotlin

Question

I only just discovered the by keyword for class, and it seems that it only works for get/set methods. But what about other methods? For example, in the code below, if I omit override fun suggestSelection(...}, it does not seem to return fallback.suggestSelection(text, selectionStartIndex, selectionEndIndex, defaultLocales);. As you see, all it does is calling the same method in fallback with the same argument. Is this the only way or is there anything to make fallback automatically called for this?
inner class MyTextClassfier(private val fallback:TextClassifier) : TextClassifier by fallback
{
override fun suggestSelection(
text: CharSequence,
selectionStartIndex: Int,
selectionEndIndex: Int,
defaultLocales: LocaleList?
): TextSelection
{
return fallback.suggestSelection(text, selectionStartIndex, selectionEndIndex, defaultLocales);
}
Adding full code as requested below. It needs the default generated Android project structure by Android Studio.
MainActivity.kt
package com.stackoverflow.test
import android.content.Context
import android.os.Bundle
import android.os.LocaleList
import android.util.Log
import android.view.textclassifier.TextClassification
import android.view.textclassifier.TextClassificationManager
import android.view.textclassifier.TextClassifier
import android.view.textclassifier.TextSelection
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity()
{
override fun onCreate(savedInstanceState: Bundle?)
{
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val textClassificationManager = getSystemService(Context.TEXT_CLASSIFICATION_SERVICE) as TextClassificationManager;
val defaultOne = textClassificationManager.textClassifier;
val txt = findViewById<TextView>(R.id.textview1);
txt.setTextClassifier(MyTextClassfier(defaultOne));
}
inner class MyTextClassfier(private val fallback:TextClassifier) : TextClassifier by fallback
{
override fun suggestSelection(
text: CharSequence,
selectionStartIndex: Int,
selectionEndIndex: Int,
defaultLocales: LocaleList?
): TextSelection
{
return fallback.suggestSelection(text, selectionStartIndex, selectionEndIndex, defaultLocales);
//return TextSelection.Builder(0,0).build();
}
override fun classifyText(
text: CharSequence,
startIndex: Int,
endIndex: Int,
defaultLocales: LocaleList?
): TextClassification
{
//Selection ended. User has lifted his finger.
Log.d("stack", "classifyText is called.");
return TextClassification.Builder().build();
}
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<TextView
android:id="#+id/textview1"
android:text="#string/large_text"
android:textAppearance="#style/TextAppearance.AppCompat.Large"
android:textIsSelectable="true"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>