Mark event-based handover constants as deprecated.

With the introduction of supported APIs in P, these event-based prototype
constants are no longer needed.

Test: Manual testing with test app
Bug: 110846969
Change-Id: Ic453923f57eb30d9ae7e1ee3c8ff07420e79f597
diff --git a/telecomm/java/android/telecom/Connection.java b/telecomm/java/android/telecom/Connection.java
index 5d5b15d..80eae14 100644
--- a/telecomm/java/android/telecom/Connection.java
+++ b/telecomm/java/android/telecom/Connection.java
@@ -584,6 +584,8 @@
      * {@link Call#EVENT_REQUEST_HANDOVER} that the handover from this {@link Connection} has
      * successfully completed.
      * @hide
+     * @deprecated Use {@link Call#handoverTo(PhoneAccountHandle, int, Bundle)} and its associated
+     * APIs instead.
      */
     public static final String EVENT_HANDOVER_COMPLETE =
             "android.telecom.event.HANDOVER_COMPLETE";
@@ -593,6 +595,8 @@
      * {@link Call#EVENT_REQUEST_HANDOVER} that the handover from this {@link Connection} has failed
      * to complete.
      * @hide
+     * @deprecated Use {@link Call#handoverTo(PhoneAccountHandle, int, Bundle)} and its associated
+     * APIs instead.
      */
     public static final String EVENT_HANDOVER_FAILED =
             "android.telecom.event.HANDOVER_FAILED";