Silent errorprone error on ignored return values

Gerrit master has a stricter errorprone settings that makes
the build fail when return values are ignored.

Change-Id: If7cc5c5e106b377d4e8537cea8c964861a023751

src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java

diff --git a/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java b/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
index 723f2d4..16f657d 100644
--- a/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
+++ b/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
@@ -25,7 +25,9 @@
 import com.google.gerrit.extensions.api.changes.RelatedChangesInfo;
 import com.google.gerrit.extensions.api.changes.SubmitInput;
 import com.google.gerrit.extensions.client.ChangeStatus;
+import com.google.gerrit.extensions.common.ChangeInfo;
 import com.google.gerrit.extensions.restapi.AuthException;
+import com.google.gerrit.extensions.restapi.Response;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.Emails;
 import com.google.gerrit.server.change.ChangeResource;
@@ -159,7 +161,7 @@
 
   /** Merge a review. */
   public void mergeReview(String project, int number) throws Exception {
-    submitter.apply(getRevisionResource(project, number), new SubmitInput());
+    Response<ChangeInfo> unused = submitter.apply(getRevisionResource(project, number), new SubmitInput());
   }
 
   public RevisionResource getRevisionResource(String project, int changeNumber) {

src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java

diff --git a/src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java b/src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java
index 83c9c75..6368c63 100644
--- a/src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java
+++ b/src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java
@@ -258,7 +258,7 @@
   }
 
   private void checkReviewExists(int reviewNumber) throws RestApiException {
-    api.changes().id(reviewNumber).get(EnumSet.of(ListChangesOption.CURRENT_REVISION));
+    ChangeInfo unused = api.changes().id(reviewNumber).get(EnumSet.of(ListChangesOption.CURRENT_REVISION));
   }
 
   @Override

src/main/java/com/criteo/gerrit/plugins/automerge/ReviewUpdater.java

diff --git a/src/main/java/com/criteo/gerrit/plugins/automerge/ReviewUpdater.java b/src/main/java/com/criteo/gerrit/plugins/automerge/ReviewUpdater.java
index 2dc1c81..de52b65 100644
--- a/src/main/java/com/criteo/gerrit/plugins/automerge/ReviewUpdater.java
+++ b/src/main/java/com/criteo/gerrit/plugins/automerge/ReviewUpdater.java
@@ -15,6 +15,8 @@
 package com.criteo.gerrit.plugins.automerge;
 
 import com.google.gerrit.extensions.api.changes.ReviewInput;
+import com.google.gerrit.extensions.api.changes.ReviewResult;
+import com.google.gerrit.extensions.restapi.Response;
 import com.google.gerrit.server.change.RevisionResource;
 import com.google.gerrit.server.restapi.change.PostReview;
 import com.google.inject.Inject;
@@ -43,6 +45,6 @@
 
   private void applyComment(String project, int number, ReviewInput comment) throws Exception {
     RevisionResource r = atomicityHelper.getRevisionResource(project, number);
-    reviewer.get().apply(r, comment);
+    Response<ReviewResult> unused = reviewer.get().apply(r, comment);
   }
 }