Be more lenient when processing group headers

We are now only looking at the contracted header instead of all
sorts of headers and if the current header is null, we don't
look any further but consider it to be equal.

Bug: 62378776
Test: add notification groups with multiple headers, observe correct icon / text behavior
Change-Id: I0b83b91caaace30df3bdcba7225e93bd0e195484
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableNotificationRow.java b/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableNotificationRow.java
index 6abf35f..ed4f685 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableNotificationRow.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableNotificationRow.java
@@ -756,6 +756,19 @@
         return getShowingLayout().getVisibleNotificationHeader();
     }
 
+
+    /**
+     * @return the contracted notification header. This can be different from
+     * {@link #getNotificationHeader()} and also {@link #getVisibleNotificationHeader()} and only
+     * returns the contracted version.
+     */
+    public NotificationHeaderView getContractedNotificationHeader() {
+        if (mIsSummaryWithChildren) {
+            return mChildrenContainer.getHeaderView();
+        }
+        return mPrivateLayout.getContractedNotificationHeader();
+    }
+
     public void setOnExpandClickListener(OnExpandClickListener onExpandClickListener) {
         mOnExpandClickListener = onExpandClickListener;
     }