Navigation Graph of sample welcome app

welcome_nav.xml

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/welcome_nav"
    app:startDestination="@id/mainFragment">

    <fragment
        android:id="@+id/mainFragment"
        android:name="com.example.prasa.navsample.ui.main.MainFragment"
        android:label="main_fragment"
        tools:layout="@layout/main_fragment">

        <action
            android:id="@+id/action_list_to_detail"
            app:destination="@id/detailFragment" />
        <action
            android:id="@+id/action_main_to_second_activity"
            app:destination="@id/secondActivity" />
        <action
            android:id="@+id/action_mainFragment_to_ageFragment"
            app:destination="@id/ageFragment" />
    </fragment>

    <fragment
        android:id="@+id/detailFragment"
        android:name="com.example.prasa.navsample.ui.welcome.WelcomeMeFragment"
        android:label="fragment_detail"
        tools:layout="@layout/fragment_detail">
        <argument
            android:name="myname"
            android:defaultValue="Prasan Pani"
            app:argType="string" />
    </fragment>

    <activity
        android:id="@+id/secondActivity"
        android:name="com.example.prasa.navsample.ui.welcome.WelcomeMeActivity"
        android:label="second_activity"
        tools:layout="@layout/activity_second">
        <argument
            android:name="myname"
            android:defaultValue="Prasan Pani"
            app:argType="string" />
    </activity>

    <fragment
        android:id="@+id/ageFragment"
        android:name="com.example.prasa.navsample.ui.age.AskMyAgeFragment"
        android:label="fragment_age"
        tools:layout="@layout/fragment_age">
        <argument
            android:name="myname"
            android:defaultValue="Prasan Pani"
            app:argType="string" />
        <action
            android:id="@+id/action_ageFragment_to_welcomeWithAgeFragment"
            app:destination="@id/welcomeWithAgeFragment" />
    </fragment>

    <fragment
        android:id="@+id/welcomeWithAgeFragment"
        android:name="com.example.prasa.navsample.ui.welcome.WelcomeMeWithAgeFragment"
        android:label="fragment_welcome_with_age"
        tools:layout="@layout/fragment_welcome_with_age">

        <argument
            android:name="myname"
            android:defaultValue="Prasan Pani"
            app:argType="string" />
        <argument
            android:name="myage"
            android:defaultValue="28"
            app:argType="integer" />
    </fragment>

</navigation>