Add Runnable overrides to ease use of Java 8 language features

Runnable and Callable are both @FunctionalInterfaces. The difference is
that Callable requires a return value whereas Runnable does not, so in
situations where we don't care about a return value, rather than having to
add an unnecessary 'return null;' at the end of the lambda, we can simply
use a non-returning Runnable instead.

Unfortunately, owing to legacy reasons, Runnable is not declared to throw
checked exceptions whereas Callable is, so in situations where checked
exceptions are thrown we still need to have a 'return null;' call at the
end.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=172935400

java/google/registry/batch/DeleteProberDataAction.java

@@ -31,8 +31,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.googlecode.objectify.Key;
-import com.googlecode.objectify.VoidWork;
-import com.googlecode.objectify.Work;
 import google.registry.config.RegistryConfig.Config;
 import google.registry.dns.DnsQueue;
 import google.registry.mapreduce.MapreduceRunner;
@@ -204,9 +202,7 @@ public class DeleteProberDataAction implements Runnable {
       final Key<EppResourceIndex> eppIndex = Key.create(EppResourceIndex.create(domainKey));
       final Key<? extends ForeignKeyIndex<?>> fki = ForeignKeyIndex.createKey(domain);
 
-      int entitiesDeleted = ofy().transact(new Work<Integer>() {
-        @Override
-        public Integer run() {
+      int entitiesDeleted = ofy().transact(() -> {
           // This ancestor query selects all descendant HistoryEntries, BillingEvents, PollMessages,
           // and TLD-specific entities, as well as the domain itself.
           List<Key<Object>> domainAndDependentKeys = ofy().load().ancestor(domainKey).keys().list();
@@ -221,16 +217,13 @@ public class DeleteProberDataAction implements Runnable {
             ofy().deleteWithoutBackup().keys(allKeys);
           }
           return allKeys.size();
-        }
-      });
+        });
       getContext().incrementCounter("domains hard-deleted");
       getContext().incrementCounter("total entities hard-deleted", entitiesDeleted);
     }
 
     private void softDeleteDomain(final DomainResource domain) {
-      ofy().transactNew(new VoidWork() {
-        @Override
-        public void vrun() {
+      ofy().transactNew(() -> {
           DomainResource deletedDomain = domain
               .asBuilder()
               .setDeletionTime(ofy().getTransactionTime())
@@ -251,7 +244,7 @@ public class DeleteProberDataAction implements Runnable {
           updateForeignKeyIndexDeletionTime(deletedDomain);
           dnsQueue.addDomainRefreshTask(deletedDomain.getFullyQualifiedDomainName());
         }
-      });
+      );
     }
   }
 }