La aplicación se ejecuta pero elTextView no se actualiza aquí es el código relevante.

activity_picker_dashboard.xml

<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- Top header -->

    <include layout="@layout/layout_header" /> This layout has databinding

    <!-- DrawerLayout -->

    <android.support.v4.widget.DrawerLayout
        android:id="@+id/drawer_layout"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@color/gray"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/toolbar">
.....

Aquí está layout_header.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable
            name="profilePayload"
            type="myms.models.ProfileResponse.Payload"/>
    </data>

<Toolbar
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/toolbar"
    android:padding="8dp"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/white">

<android.support.constraint.ConstraintLayout
    android:id="@+id/header"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"

    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

    <ImageView
        android:layout_width="180dp"
        android:layout_height="60dp"
        android:adjustViewBounds="true"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        android:src="@drawable/logo_color"/>

    <TextView
        android:id="@+id/username"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:text="@{profilePayload.firstName}" Here it is
        android:textColor="@color/red"
        android:textSize="18sp"
        app:layout_constraintBottom_toTopOf="@+id/role"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_chainStyle="packed" />

...............
</Toolbar>
</layout>

Aquí está mi modelo ProfileResponse.java

public class ProfileResponse
{
    public Payload getPayLoad() {
        return payLoad;
    }

    @SerializedName("Payload")
    private Payload payLoad;

    public static class Payload
    {
        public String getProfileId() {
            return profileId;
        }

        public String getUserId() {
            return userId;
        }

        public String getFirstName() {
            return firstName;
        }

        public String getLastName() {
            return lastName;
        }

        @SerializedName("ProfileId")
        private String profileId;

        @SerializedName("UserId")
        private String userId;

        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }

        public void setLastName(String lastName) {
            this.lastName = lastName;
        }

        @SerializedName("FirstName")

        private String firstName;

        @SerializedName("LastName")
        private String lastName;
    }
}

Y finalmente esta es mi actividad

 public class PickerDashboardActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_picker_dashboard);

        LayoutHeaderBinding binding = LayoutHeaderBinding.inflate(getLayoutInflater());

        ProfileResponse.Payload profilePayload = new ProfileResponse.Payload();
        profilePayload.setFirstName("Test");

        binding.setProfilePayload(profilePayload);

        ButterKnife.bind(this);
}

Por favor sugiera una solución. He estado intentando esto por bastante tiempo ahora. P.S: También estoy usando un cuchillo de mantequilla.