Use Arrays.hashCode in EventIndex hashCode()

The hashCode method on arrays does not actually hash the array contents
but instead is just the identity of the array itself. This will return
erroneous results for objects that are equal but not the exact same
instance.

Bug: 217923092
Test: errorprone build
Change-Id: Idfcc220da5fb07a9b24a7b12795466303b14e35a

services/Android.bp

@@ -21,6 +21,7 @@ java_defaults {
             "-Xep:TryFailThrowable:ERROR",
             "-Xep:HashtableContains:ERROR",
             "-Xep:FormatString:ERROR",
+            "-Xep:ArrayHashCode:ERROR",
             // NOTE: only enable to generate local patchfiles
             // "-XepPatchChecks:refaster:frameworks/base/errorprone/refaster/EfficientXml.java.refaster",
             // "-XepPatchLocation:/tmp/refaster/",

services/people/java/com/android/server/people/data/EventIndex.java

@@ -254,7 +254,7 @@ public class EventIndex {
 
     @Override
     public int hashCode() {
-        return Objects.hash(mLastUpdatedTime, mEventBitmaps);
+        return Objects.hash(mLastUpdatedTime, Arrays.hashCode(mEventBitmaps));
     }
 
     synchronized void writeToProto(@NonNull ProtoOutputStream protoOutputStream) {