marker_cluster_grouped.axml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="@dimen/marker_cluster_grouped_imageview_size"
    android:layout_height="@dimen/marker_cluster_grouped_imageview_size">
    <ImageView
        android:id="@+id/marker_cluster_grouped_imageview"
        android:layout_width="@dimen/marker_cluster_grouped_imageview_size"
        android:layout_height="@dimen/marker_cluster_grouped_imageview_size" />
    <TextView
        android:id="@id/amu_text" 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="@android:color/white"
        android:textStyle="bold"
        android:textSize="14sp"
        android:background="@android:color/transparent"
        android:layout_gravity="center" />
</FrameLayout>