Replace the deprecated RefDatabase.getRef with findRef

JGit has deprecated the use of getRef and findRef should
be used instead.

Change-Id: I32d3ed379eb115fbbe08783e01701d0f4eb4699b
diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidator.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidator.java
index dcc9030..89c6792 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidator.java
@@ -244,7 +244,7 @@
   }
 
   protected Ref getCurrentRef(String refName) throws IOException {
-    return MoreObjects.firstNonNull(refDb.getRef(refName), nullRef(refName));
+    return MoreObjects.firstNonNull(refDb.findRef(refName), nullRef(refName));
   }
 
   public static class CloseableSet<T extends AutoCloseable> implements AutoCloseable {
diff --git a/src/test/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidatorTest.java
index de93545..3f4d1bb 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidatorTest.java
@@ -67,7 +67,7 @@
     newUpdateRef = newRef(refName, AN_OBJECT_ID_2);
     localRef = newRef(refName, AN_OBJECT_ID_3);
 
-    doReturn(localRef).when(localRefDb).getRef(refName);
+    doReturn(localRef).when(localRefDb).findRef(refName);
     doReturn(localRef).when(localRefDb).exactRef(refName);
     doReturn(oldUpdateRef).when(refUpdate).getRef();
     doReturn(newUpdateRef.getObjectId()).when(refUpdate).getNewObjectId();
@@ -118,7 +118,7 @@
     doReturn(true)
         .when(sharedRefDb)
         .compareAndPut(A_TEST_PROJECT_NAME_KEY, localRef, ObjectId.zeroId());
-    doReturn(localRef).doReturn(null).when(localRefDb).getRef(refName);
+    doReturn(localRef).doReturn(null).when(localRefDb).findRef(refName);
 
     Result result = refUpdateValidator.executeRefUpdate(refUpdate, () -> RefUpdate.Result.FORCED);
 
@@ -137,7 +137,7 @@
     doReturn(true)
         .when(sharedRefDb)
         .compareAndPut(A_TEST_PROJECT_NAME_KEY, localNullRef, newUpdateRef.getObjectId());
-    doReturn(localNullRef).doReturn(newUpdateRef).when(localRefDb).getRef(refName);
+    doReturn(localNullRef).doReturn(newUpdateRef).when(localRefDb).findRef(refName);
 
     Result result = refUpdateValidator.executeRefUpdate(refUpdate, () -> RefUpdate.Result.NEW);