Make BoundingArc immutable

We don't need mutability for BoundingArc.

Test: N/A
Relnote: The experimental BoundingArc class is now immutable.
Change-Id: If624a586111c5a57fe5c8da35f430a8cc5a9fa13
diff --git a/wear/watchface/watchface/api/public_plus_experimental_current.txt b/wear/watchface/watchface/api/public_plus_experimental_current.txt
index 233ddf0..4cf90dc 100644
--- a/wear/watchface/watchface/api/public_plus_experimental_current.txt
+++ b/wear/watchface/watchface/api/public_plus_experimental_current.txt
@@ -11,9 +11,6 @@
     method public float getThickness();
     method public float getTotalAngle();
     method public boolean hitTest(android.graphics.Rect rect, @Px float x, @Px float y);
-    method public void setStartAngle(float);
-    method public void setThickness(float);
-    method public void setTotalAngle(float);
     property public final float startAngle;
     property public final float thickness;
     property public final float totalAngle;
diff --git a/wear/watchface/watchface/src/main/java/androidx/wear/watchface/ComplicationSlot.kt b/wear/watchface/watchface/src/main/java/androidx/wear/watchface/ComplicationSlot.kt
index 3679997..279dd52 100644
--- a/wear/watchface/watchface/src/main/java/androidx/wear/watchface/ComplicationSlot.kt
+++ b/wear/watchface/watchface/src/main/java/androidx/wear/watchface/ComplicationSlot.kt
@@ -252,7 +252,7 @@
  * min(boundingRect.width, boundingRect.height).
  */
 @ComplicationExperimental
-public class BoundingArc(var startAngle: Float, var totalAngle: Float, @Px var thickness: Float) {
+public class BoundingArc(val startAngle: Float, val totalAngle: Float, @Px val thickness: Float) {
     /**
      * Detects whether the supplied point falls within the edge complication's arc.
      *