Firebase data insert issue. Data is not inserted properly
<p>I am trying to insert a POJO to Firebase. However, some of the fields don't seem to be parsed into Firebase, but there is no warning or error.</p>

<p>I have this POJO:   </p>

<pre><code>public class Group {
    public String name;
    public String admin;
    public List&lt;String&gt; addedUsers;
    public List&lt;String&gt; invitedUsers;

    public Group(String name, String admin, ArrayList&lt;String&gt; addedUsers, ArrayList&lt;String&gt; invitedUsers) {
        this.name = name;
        this.admin = admin;
        this.addedUsers = addedUsers;
        this.invitedUsers = invitedUsers;
    }

    public Group() {
        // Default constructor required because we have a non-default constructor as well.
    }
}
</code></pre>

<p>I upload to Firebase by doing so:</p>

<pre><code>DatabaseReference groupRef = ref.child("Groups");
ArrayList&lt;String&gt; addedUsers = new ArrayList&lt;String&gt;();
addedUsers.add("email1@gmail.com");
addedUsers.add("email2@gmail.com");
ArrayList&lt;String&gt; invitedUsers = new ArrayList&lt;String&gt;();
Group newGroup = new Group("GroupName",
        "email1@gmail.com", addedUsers, invitedUsers
);

groupRef.push().setValue(newGroup);
</code></pre>

<p>I end up with this object in Firebase:</p>

<p><a href="https://i.stack.imgur.com/JalHt.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JalHt.png" alt="enter image description here"></a></p>

<p>I have a secondary issue now, I manually inserted the data into Firebase, but now I cannot map the Lists onto my Java Object, and are mapped as null, I know I am able to download the data fine;</p>