Fix based on feedback

Author: brfrn169

core/src/main/java/com/scalar/db/transaction/consensuscommit/CrudHandler.java

@@ -43,10 +43,11 @@
 import java.util.stream.Collectors;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
+import javax.annotation.concurrent.ThreadSafe;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-@NotThreadSafe
+@ThreadSafe
 public class CrudHandler {
   private static final Logger logger = LoggerFactory.getLogger(CrudHandler.class);
   private final DistributedStorage storage;