Expose WindowCongifuration#getDisplayRotation as TestApi

To allow adding CTS against the display rotation.

Fix: 317008588
Test: m
Change-Id: If1be3661ae6dc9d87c62ebfece9f9cea0051dd75
diff --git a/core/api/test-current.txt b/core/api/test-current.txt
index 42daea2..ee9af5a 100644
--- a/core/api/test-current.txt
+++ b/core/api/test-current.txt
@@ -507,6 +507,7 @@
     method public int getActivityType();
     method @Nullable public android.graphics.Rect getAppBounds();
     method @NonNull public android.graphics.Rect getBounds();
+    method public int getDisplayRotation();
     method @NonNull public android.graphics.Rect getMaxBounds();
     method public int getRotation();
     method public int getWindowingMode();
diff --git a/core/java/android/app/WindowConfiguration.java b/core/java/android/app/WindowConfiguration.java
index 4621634..aa3b71a 100644
--- a/core/java/android/app/WindowConfiguration.java
+++ b/core/java/android/app/WindowConfiguration.java
@@ -27,6 +27,7 @@
 import android.annotation.IntDef;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
+import android.annotation.SuppressLint;
 import android.annotation.TestApi;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.content.res.Configuration;
@@ -326,7 +327,7 @@
     }
 
     /**
-     * Sets the apparent display cutout.
+     * Sets the display rotation.
      * @hide
      */
     public void setDisplayRotation(@Surface.Rotation int rotation) {
@@ -386,9 +387,9 @@
     }
 
     /**
-     * @see #setDisplayRotation
-     * @hide
+     * Gets the display rotation.
      */
+    @SuppressLint("UnflaggedApi") // @TestApi without associated feature.
     public @Surface.Rotation int getDisplayRotation() {
         return mDisplayRotation;
     }