diff --git a/BUILD b/BUILD
index 0c83ab9..a5fa04e 100644
--- a/BUILD
+++ b/BUILD
@@ -6,7 +6,7 @@
     srcs = glob(["src/main/java/**/*.java"]),
     manifest_entries = [
         "Gerrit-PluginName: uploadvalidator",
-        "Gerrit-ApiVersion: 2.14-SNAPSHOT",
+        "Gerrit-ApiVersion: 2.15-SNAPSHOT",
         "Gerrit-Module: com.googlesource.gerrit.plugins.uploadvalidator.Module",
     ],
     resources = glob(["src/main/resources/**/*"]),
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/BlockedKeywordValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/BlockedKeywordValidator.java
index bd5420e..c8fa506 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/BlockedKeywordValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/BlockedKeywordValidator.java
@@ -43,6 +43,7 @@
 import org.eclipse.jgit.lib.ObjectLoader;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -123,8 +124,12 @@
         try (Repository repo =
             repoManager.openRepository(receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages =
-              performValidation(repo, receiveEvent.commit,
-                  blockedKeywordPatterns.values(), cfg);
+              performValidation(
+                  repo,
+                  receiveEvent.commit,
+                  receiveEvent.revWalk,
+                  blockedKeywordPatterns.values(),
+                  cfg);
           if (!messages.isEmpty()) {
             throw new CommitValidationException(
                 "includes files containing blocked keywords", messages);
@@ -139,13 +144,18 @@
   }
 
   @VisibleForTesting
-  List<CommitValidationMessage> performValidation(Repository repo, RevCommit c,
-      ImmutableCollection<Pattern> blockedKeywordPartterns, PluginConfig cfg)
-          throws IOException, ExecutionException {
+  List<CommitValidationMessage> performValidation(
+      Repository repo,
+      RevCommit c,
+      RevWalk revWalk,
+      ImmutableCollection<Pattern> blockedKeywordPartterns,
+      PluginConfig cfg)
+      throws IOException, ExecutionException {
     List<CommitValidationMessage> messages = new LinkedList<>();
     checkCommitMessageForBlockedKeywords(blockedKeywordPartterns, messages,
         c.getFullMessage());
-    Map<String, ObjectId> content = CommitUtils.getChangedContent(repo, c);
+    Map<String, ObjectId> content = CommitUtils.getChangedContent(
+        repo, c, revWalk);
     for (String path : content.keySet()) {
       ObjectLoader ol = repo.open(content.get(path));
       if (contentTypeUtil.isBinary(ol, path, cfg)) {
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/CommitUtils.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/CommitUtils.java
index 8b622ab..0da4894 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/CommitUtils.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/CommitUtils.java
@@ -27,6 +27,7 @@
 import java.util.Map;
 import java.util.Set;
 
+/** Utility class for checking whether commits are different. */
 public class CommitUtils {
 
   /**
@@ -39,9 +40,12 @@
    *     passed commit and its parents.
    * @throws IOException
    */
-  public static Set<String> getChangedPaths(Repository repo, RevCommit c)
+  public static Set<String> getChangedPaths(
+      Repository repo,
+      RevCommit c,
+      RevWalk revWalk)
       throws IOException {
-    Map<String, ObjectId> content = getChangedContent(repo, c);
+    Map<String, ObjectId> content = getChangedContent(repo, c, revWalk);
     return content.keySet();
   }
 
@@ -61,10 +65,10 @@
    * @throws IOException
    */
   public static Map<String, ObjectId> getChangedContent(Repository repo,
-      RevCommit c) throws IOException {
+      RevCommit c, RevWalk revWalk) throws IOException {
     final Map<String, ObjectId> content = new HashMap<>();
 
-    visitChangedEntries(repo, c, new TreeWalkVisitor() {
+    visitChangedEntries(repo, c, revWalk, new TreeWalkVisitor() {
       @Override
       public void onVisit(TreeWalk tw) {
         if (isFile(tw)) {
@@ -90,29 +94,21 @@
    * @param visitor A TreeWalkVisitor with the desired action
    * @throws IOException
    */
-  public static void visitChangedEntries(Repository repo, RevCommit c,
+  public static void visitChangedEntries(
+      Repository repo,
+      RevCommit c,
+      RevWalk revWalk,
       TreeWalkVisitor visitor) throws IOException {
-    try (TreeWalk tw = new TreeWalk(repo)) {
+    try (TreeWalk tw = new TreeWalk(revWalk.getObjectReader())) {
       tw.setRecursive(true);
       tw.setFilter(TreeFilter.ANY_DIFF);
       tw.addTree(c.getTree());
       if (c.getParentCount() > 0) {
-        @SuppressWarnings("resource")
-        RevWalk rw = null;
-        try {
-          for (RevCommit p : c.getParents()) {
-            if (p.getTree() == null) {
-              if (rw == null) {
-                rw = new RevWalk(repo);
-              }
-              rw.parseHeaders(p);
-            }
-            tw.addTree(p.getTree());
+        for (RevCommit p : c.getParents()) {
+          if (p.getTree() == null) {
+            revWalk.parseHeaders(p);
           }
-        } finally {
-          if (rw != null) {
-            rw.close();
-          }
+          tw.addTree(p.getTree());
         }
         while (tw.next()) {
           if (isDifferentToAllParents(c, tw)) {
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/ContentTypeValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/ContentTypeValidator.java
index ed236e1..f792cdb 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/ContentTypeValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/ContentTypeValidator.java
@@ -36,6 +36,7 @@
 import org.eclipse.jgit.lib.ObjectStream;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -121,7 +122,7 @@
         try (Repository repo =
             repoManager.openRepository(receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages =
-              performValidation(repo, receiveEvent.commit, getBlockedTypes(cfg),
+              performValidation(repo, receiveEvent.commit, receiveEvent.revWalk, getBlockedTypes(cfg),
                   isWhitelist(cfg));
           if (!messages.isEmpty()) {
             throw new CommitValidationException("contains blocked content type",
@@ -137,10 +138,10 @@
 
   @VisibleForTesting
   List<CommitValidationMessage> performValidation(Repository repo,
-      RevCommit c, String[] blockedTypes, boolean whitelist)
+      RevCommit c, RevWalk revWalk, String[] blockedTypes, boolean whitelist)
       throws IOException, ExecutionException {
     List<CommitValidationMessage> messages = new LinkedList<>();
-    Map<String, ObjectId> content = CommitUtils.getChangedContent(repo, c);
+    Map<String, ObjectId> content = CommitUtils.getChangedContent(repo, c, revWalk);
     for (String path : content.keySet()) {
       ObjectLoader ol = repo.open(content.get(path));
       try (ObjectStream os = ol.openStream()) {
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/DuplicatePathnameValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/DuplicatePathnameValidator.java
index 72ae551..2a80d38 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/DuplicatePathnameValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/DuplicatePathnameValidator.java
@@ -38,6 +38,7 @@
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.treewalk.TreeWalk;
+import org.eclipse.jgit.revwalk.RevWalk;
 
 import java.io.IOException;
 import java.util.Arrays;
@@ -179,7 +180,7 @@
         try (Repository repo =
             repoManager.openRepository(receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages =
-              performValidation(repo, receiveEvent.commit);
+              performValidation(repo, receiveEvent.commit, receiveEvent.revWalk);
           if (!messages.isEmpty()) {
             throw new CommitValidationException("contains duplicate pathnames",
                 messages);
@@ -194,11 +195,11 @@
   }
 
   @VisibleForTesting
-  List<CommitValidationMessage> performValidation(Repository repo, RevCommit c)
+  List<CommitValidationMessage> performValidation(Repository repo, RevCommit c, RevWalk revWalk)
       throws IOException {
     List<CommitValidationMessage> messages = new LinkedList<>();
 
-    Set<String> pathnames = CommitUtils.getChangedPaths(repo, c);
+    Set<String> pathnames = CommitUtils.getChangedPaths(repo, c, revWalk);
     checkForDuplicatesInSet(pathnames, messages);
     if (!messages.isEmpty() || c.getParentCount() == 0) {
       return messages;
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/FileExtensionValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/FileExtensionValidator.java
index 79cac3f..3c0df3d 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/FileExtensionValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/FileExtensionValidator.java
@@ -32,6 +32,7 @@
 
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -103,7 +104,7 @@
         try (Repository repo =
             repoManager.openRepository(receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages = performValidation(repo,
-              receiveEvent.commit, getBlockedExtensions(cfg));
+              receiveEvent.commit, receiveEvent.revWalk, getBlockedExtensions(cfg));
           if (!messages.isEmpty()) {
             throw new CommitValidationException(
                 "contains files with blocked file extensions", messages);
@@ -117,9 +118,9 @@
   }
 
   static List<CommitValidationMessage> performValidation(Repository repo,
-      RevCommit c, List<String> blockedFileExtensions) throws IOException {
+      RevCommit c, RevWalk revWalk, List<String> blockedFileExtensions) throws IOException {
     List<CommitValidationMessage> messages = new LinkedList<>();
-    for (String file : CommitUtils.getChangedPaths(repo, c)) {
+    for (String file : CommitUtils.getChangedPaths(repo, c, revWalk)) {
       for (String blockedExtension : blockedFileExtensions) {
         if (file.toLowerCase().endsWith(blockedExtension.toLowerCase())) {
           messages.add(new CommitValidationMessage("blocked file: " + file, true));
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidFilenameValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidFilenameValidator.java
index e2fd516..d0906ff 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidFilenameValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidFilenameValidator.java
@@ -32,6 +32,7 @@
 
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -96,7 +97,7 @@
         try (Repository repo = repoManager.openRepository(
             receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages =
-              performValidation(repo, receiveEvent.commit,
+              performValidation(repo, receiveEvent.commit, receiveEvent.revWalk,
                   cfg.getStringList(KEY_INVALID_FILENAME_PATTERN));
           if (!messages.isEmpty()) {
             throw new CommitValidationException(
@@ -112,13 +113,13 @@
   }
 
   static List<CommitValidationMessage> performValidation(Repository repo,
-      RevCommit c, String[] patterns) throws IOException {
+      RevCommit c, RevWalk revWalk, String[] patterns) throws IOException {
     List<Pattern> invalidFilenamePatterns = new ArrayList<>();
     for (String s : patterns) {
       invalidFilenamePatterns.add(Pattern.compile(s));
     }
     List<CommitValidationMessage> messages = new LinkedList<>();
-    for (String file : CommitUtils.getChangedPaths(repo, c)) {
+    for (String file : CommitUtils.getChangedPaths(repo, c, revWalk)) {
       for (Pattern p : invalidFilenamePatterns) {
         if (p.matcher(file).find()) {
           messages.add(new CommitValidationMessage(
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidLineEndingValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidLineEndingValidator.java
index 559b745..e3c44f1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidLineEndingValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidLineEndingValidator.java
@@ -35,6 +35,7 @@
 import org.eclipse.jgit.lib.ObjectLoader;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 
 import java.io.IOException;
 import java.io.InputStreamReader;
@@ -106,7 +107,7 @@
         try (Repository repo =
             repoManager.openRepository(receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages =
-              performValidation(repo, receiveEvent.commit, cfg);
+              performValidation(repo, receiveEvent.commit, receiveEvent.revWalk, cfg);
           if (!messages.isEmpty()) {
             throw new CommitValidationException(
                 "contains files with a Windows line ending", messages);
@@ -121,10 +122,10 @@
   }
 
   @VisibleForTesting
-  List<CommitValidationMessage> performValidation(Repository repo, RevCommit c,
+  List<CommitValidationMessage> performValidation(Repository repo, RevCommit c, RevWalk revWalk,
       PluginConfig cfg) throws IOException, ExecutionException {
     List<CommitValidationMessage> messages = new LinkedList<>();
-    Map<String, ObjectId> content = CommitUtils.getChangedContent(repo, c);
+    Map<String, ObjectId> content = CommitUtils.getChangedContent(repo, c, revWalk);
     for (String path : content.keySet()) {
       ObjectLoader ol = repo.open(content.get(path));
       if (contentTypeUtil.isBinary(ol, path, cfg)) {
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/MaxPathLengthValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/MaxPathLengthValidator.java
index 53dc2e3..29aeba8 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/MaxPathLengthValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/MaxPathLengthValidator.java
@@ -31,6 +31,7 @@
 
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -92,7 +93,7 @@
         try (Repository repo =
             repoManager.openRepository(receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages =
-              performValidation(repo, receiveEvent.commit, maxPathLength);
+              performValidation(repo, receiveEvent.commit, receiveEvent.revWalk, maxPathLength);
           if (!messages.isEmpty()) {
             throw new CommitValidationException(
                 "contains files with too long paths (max path length: "
@@ -108,9 +109,9 @@
   }
 
   static List<CommitValidationMessage> performValidation(Repository repo,
-      RevCommit c, int maxPathLength) throws IOException {
+      RevCommit c, RevWalk revWalk, int maxPathLength) throws IOException {
     List<CommitValidationMessage> messages = new LinkedList<>();
-    for (String file : CommitUtils.getChangedPaths(repo, c)) {
+    for (String file : CommitUtils.getChangedPaths(repo, c, revWalk)) {
       if (file.length() > maxPathLength) {
         messages.add(new CommitValidationMessage("path too long: " + file, true));
       }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/SubmoduleValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/SubmoduleValidator.java
index 5dd9ee5..88c8f62 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/SubmoduleValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/SubmoduleValidator.java
@@ -33,6 +33,7 @@
 import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.treewalk.TreeWalk;
 
 import java.io.IOException;
@@ -93,7 +94,7 @@
         try (Repository repo =
             repoManager.openRepository(receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages =
-              performValidation(repo, receiveEvent.commit);
+              performValidation(repo, receiveEvent.commit, receiveEvent.revWalk);
           if (!messages.isEmpty()) {
             throw new CommitValidationException("contains submodules", messages);
           }
@@ -116,10 +117,10 @@
   }
 
   static List<CommitValidationMessage> performValidation(Repository repo,
-      RevCommit c) throws IOException {
+      RevCommit c, RevWalk revWalk) throws IOException {
     final List<CommitValidationMessage> messages = new LinkedList<>();
 
-    CommitUtils.visitChangedEntries(repo, c, new TreeWalkVisitor() {
+    CommitUtils.visitChangedEntries(repo, c, revWalk, new TreeWalkVisitor() {
       @Override
       public void onVisit(TreeWalk tw) {
         if (isSubmodule(tw)) {
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/SymlinkValidator.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/SymlinkValidator.java
index 572600c..381cc7b 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/SymlinkValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/SymlinkValidator.java
@@ -33,6 +33,7 @@
 import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.treewalk.TreeWalk;
 
 import java.io.IOException;
@@ -94,7 +95,7 @@
         try (Repository repo =
             repoManager.openRepository(receiveEvent.project.getNameKey())) {
           List<CommitValidationMessage> messages =
-              performValidation(repo, receiveEvent.commit);
+              performValidation(repo, receiveEvent.commit, receiveEvent.revWalk);
           if (!messages.isEmpty()) {
             throw new CommitValidationException("contains symbolic links",
                 messages);
@@ -120,10 +121,10 @@
   }
 
   static List<CommitValidationMessage> performValidation(Repository repo,
-      RevCommit c) throws IOException {
+      RevCommit c, RevWalk revWalk) throws IOException {
     final List<CommitValidationMessage> messages = new LinkedList<>();
 
-    CommitUtils.visitChangedEntries(repo, c, new TreeWalkVisitor() {
+    CommitUtils.visitChangedEntries(repo, c, revWalk, new TreeWalkVisitor() {
       @Override
       public void onVisit(TreeWalk tw) {
         if (isSymLink(tw)) {
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/BlockedKeywordValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/BlockedKeywordValidatorTest.java
index c2a92e5..2ec5dd7 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/BlockedKeywordValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/BlockedKeywordValidatorTest.java
@@ -25,6 +25,7 @@
 
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.junit.Test;
 
 import java.io.File;
@@ -46,7 +47,7 @@
         .build();
   }
 
-  private RevCommit makeCommit() throws IOException, GitAPIException {
+  private RevCommit makeCommit(RevWalk rw) throws IOException, GitAPIException {
     Map<File, byte[]> files = new HashMap<>();
     // invalid files
     String content = "http://foo.bar.tld/?pw=myp4ssw0rdTefoobarstline2\n";
@@ -68,25 +69,27 @@
         + "Testline4";
     files.put(new File(repo.getDirectory().getParent(), "foobar.txt"),
         content.getBytes(StandardCharsets.UTF_8));
-    return TestUtils.makeCommit(repo, "Commit foobar with test files.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit foobar with test files.", files);
   }
 
   @Test
   public void testKeywords() throws Exception {
-    RevCommit c = makeCommit();
-    BlockedKeywordValidator validator = new BlockedKeywordValidator(null,
-        new ContentTypeUtil(PATTERN_CACHE), PATTERN_CACHE, null, null, null);
-    List<CommitValidationMessage> m = validator.performValidation(
-        repo, c, getPatterns().values(), EMPTY_PLUGIN_CONFIG);
-    Set<String> expected = ImmutableSet.of(
-        "ERROR: blocked keyword(s) found in: foo.txt (Line: 1)"
-            + " (found: myp4ssw0rd, foobar)",
-        "ERROR: blocked keyword(s) found in: bar.txt (Line: 5)"
-            + " (found: $Id: foo bar$)",
-        "ERROR: blocked keyword(s) found in: " + Patch.COMMIT_MSG
-            + " (Line: 1) (found: foobar)");
-    assertThat(TestUtils.transformMessages(m))
-        .containsExactlyElementsIn(expected);
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommit(rw);
+      BlockedKeywordValidator validator = new BlockedKeywordValidator(null,
+          new ContentTypeUtil(PATTERN_CACHE), PATTERN_CACHE, null, null, null);
+      List<CommitValidationMessage> m = validator.performValidation(
+          repo, c, rw, getPatterns().values(), EMPTY_PLUGIN_CONFIG);
+      Set<String> expected = ImmutableSet.of(
+          "ERROR: blocked keyword(s) found in: foo.txt (Line: 1)"
+              + " (found: myp4ssw0rd, foobar)",
+          "ERROR: blocked keyword(s) found in: bar.txt (Line: 5)"
+              + " (found: $Id: foo bar$)",
+          "ERROR: blocked keyword(s) found in: " + Patch.COMMIT_MSG
+              + " (Line: 1) (found: foobar)");
+      assertThat(TestUtils.transformMessages(m))
+          .containsExactlyElementsIn(expected);
+    }
   }
 
   @Test
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/ContentTypeValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/ContentTypeValidatorTest.java
index edad751..75f1b07 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/ContentTypeValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/ContentTypeValidatorTest.java
@@ -22,6 +22,7 @@
 
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -65,22 +66,26 @@
     String[] patterns =
         new String[] {"application/pdf", "application/xml", "text/html"};
 
-    List<CommitValidationMessage> m = validator.performValidation(
-        repo, makeCommit(), patterns, false);
-    assertThat(TestUtils.transformMessages(m)).containsExactly(
-        "ERROR: found blocked content type (application/pdf) in file: foo.pdf",
-        "ERROR: found blocked content type (application/xml) in file: foo.xml",
-        "ERROR: found blocked content type (text/html) in file: foo.html");
+    try (RevWalk rw = new RevWalk(repo)) {
+      List<CommitValidationMessage> m = validator.performValidation(
+          repo, makeCommit(rw), rw, patterns, false);
+      assertThat(TestUtils.transformMessages(m)).containsExactly(
+          "ERROR: found blocked content type (application/pdf) in file: foo.pdf",
+          "ERROR: found blocked content type (application/xml) in file: foo.xml",
+          "ERROR: found blocked content type (text/html) in file: foo.html");
+    }
   }
 
   @Test
   public void testWhitelist() throws Exception {
     String[] patterns = new String[] {"application/pdf", "application/xml"};
 
-    List<CommitValidationMessage> m = validator.performValidation(
-        repo, makeCommit(), patterns, true);
-    assertThat(TestUtils.transformMessages(m)).containsExactly(
-        "ERROR: found blocked content type (text/html) in file: foo.html");
+    try (RevWalk rw = new RevWalk(repo)) {
+      List<CommitValidationMessage> m = validator.performValidation(
+          repo, makeCommit(rw), rw, patterns, true);
+      assertThat(TestUtils.transformMessages(m)).containsExactly(
+          "ERROR: found blocked content type (text/html) in file: foo.html");
+    }
   }
 
   @Test
@@ -89,7 +94,7 @@
     assertThat(ContentTypeValidator.isWhitelist(EMPTY_PLUGIN_CONFIG)).isFalse();
   }
 
-  private RevCommit makeCommit() throws IOException, GitAPIException {
+  private RevCommit makeCommit(RevWalk rw) throws IOException, GitAPIException {
     Map<File, byte[]> files = new HashMap<>();
 
     String content = "<?xml version=\"1.0\"?><a><b>c</b></a>";
@@ -101,6 +106,6 @@
         content.getBytes(StandardCharsets.UTF_8));
 
     files.put(TestUtils.createEmptyFile("foo.pdf", repo), TEST_PDF);
-    return TestUtils.makeCommit(repo, "Commit with test files.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit with test files.", files);
   }
 }
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/DuplicatePathnameValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/DuplicatePathnameValidatorTest.java
index 2461bf6..cc0cee3 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/DuplicatePathnameValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/DuplicatePathnameValidatorTest.java
@@ -33,6 +33,7 @@
 import org.eclipse.jgit.junit.TestRepository;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.treewalk.TreeWalk;
 import org.junit.Before;
 import org.junit.Test;
@@ -57,10 +58,10 @@
   private DuplicatePathnameValidator validator;
 
   private void runCheck(List<String> existingTreePaths, Set<String> testPaths,
-      List<CommitValidationMessage> messages, List<String> visitedPaths)
-          throws Exception {
+    List<CommitValidationMessage> messages, List<String> visitedPaths)
+        throws Exception {
     RevCommit c = makeCommit(
-        createEmptyDirCacheEntries(existingTreePaths, testRepo), testRepo);
+        testRepo.getRevWalk(), createEmptyDirCacheEntries(existingTreePaths, testRepo), testRepo);
     try (TreeWalk tw = new TreeWalk(repo)) {
       tw.setRecursive(false);
       tw.addTree(c.getTree());
@@ -136,44 +137,48 @@
     filenames.add("A");
     filenames.add("F1/ab");
     filenames.add("f2/sF1/aB");
-    RevCommit c =
-        makeCommit(createEmptyDirCacheEntries(filenames, testRepo), testRepo);
-    List<CommitValidationMessage> m = validator.performValidation(repo, c);
-    assertThat(m).hasSize(4);
-    // During checking inside of the commit it's unknown which file is checked
-    // first, because of that, both capabilities must be checked.
-    assertThat(transformMessages(m)).containsAnyOf(
-        transformMessage(conflict("A", "a")),
-        transformMessage(conflict("a", "A")));
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c =
+          makeCommit(rw, createEmptyDirCacheEntries(filenames, testRepo), testRepo);
+      List<CommitValidationMessage> m = validator.performValidation(repo, c, rw);
+      assertThat(m).hasSize(4);
+      // During checking inside of the commit it's unknown which file is checked
+      // first, because of that, both capabilities must be checked.
+      assertThat(transformMessages(m)).containsAnyOf(
+          transformMessage(conflict("A", "a")),
+          transformMessage(conflict("a", "A")));
 
-    assertThat(transformMessages(m)).containsAnyOf(
-        transformMessage(conflict("F1", "f1")),
-        transformMessage(conflict("f1", "F1")));
+      assertThat(transformMessages(m)).containsAnyOf(
+          transformMessage(conflict("F1", "f1")),
+          transformMessage(conflict("f1", "F1")));
 
-    assertThat(transformMessages(m)).containsAnyOf(
-        transformMessage(conflict("F1/ab", "f1/ab")),
-        transformMessage(conflict("f1/ab", "F1/ab")));
+      assertThat(transformMessages(m)).containsAnyOf(
+          transformMessage(conflict("F1/ab", "f1/ab")),
+          transformMessage(conflict("f1/ab", "F1/ab")));
 
-    assertThat(transformMessages(m)).containsAnyOf(
-        transformMessage(
-            conflict("f2/sF1/aB", "f2/sF1/ab")),
-        transformMessage(
-            conflict("f2/sF1/ab", "f2/sF1/aB")));
+      assertThat(transformMessages(m)).containsAnyOf(
+          transformMessage(
+              conflict("f2/sF1/aB", "f2/sF1/ab")),
+          transformMessage(
+              conflict("f2/sF1/ab", "f2/sF1/aB")));
+    }
   }
 
   @Test
   public void testCheckRenaming() throws Exception {
-    RevCommit c = makeCommit(
-        createEmptyDirCacheEntries(INITIAL_PATHNAMES, testRepo), testRepo);
-    DirCacheEntry[] entries = new DirCacheEntry[INITIAL_PATHNAMES.size()];
-    for (int x = 0; x < INITIAL_PATHNAMES.size(); x++) {
-      // Rename files
-      entries[x] = createDirCacheEntry(INITIAL_PATHNAMES.get(x).toUpperCase(),
-          EMPTY_CONTENT, testRepo);
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommit(
+          rw, createEmptyDirCacheEntries(INITIAL_PATHNAMES, testRepo), testRepo);
+      DirCacheEntry[] entries = new DirCacheEntry[INITIAL_PATHNAMES.size()];
+      for (int x = 0; x < INITIAL_PATHNAMES.size(); x++) {
+        // Rename files
+        entries[x] = createDirCacheEntry(INITIAL_PATHNAMES.get(x).toUpperCase(),
+            EMPTY_CONTENT, testRepo);
+      }
+      RevCommit c1 = makeCommit(rw, entries, testRepo, c);
+      List<CommitValidationMessage> m = validator.performValidation(repo, c1, rw);
+      assertThat(m).isEmpty();
     }
-    RevCommit c1 = makeCommit(entries, testRepo, c);
-    List<CommitValidationMessage> m = validator.performValidation(repo, c1);
-    assertThat(m).isEmpty();
   }
 
   @Test
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/FileExtensionValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/FileExtensionValidatorTest.java
index 0b8af8a..5ee046c 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/FileExtensionValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/FileExtensionValidatorTest.java
@@ -23,6 +23,7 @@
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.api.errors.NoFilepatternException;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.junit.Test;
 
 import java.io.File;
@@ -38,7 +39,7 @@
   private static final List<String> BLOCKED_EXTENSIONS_UC =
       Lists.newArrayList("JPEG", "PDF", "ZIP", "EXE", "TAR.GZ");
 
-  private RevCommit makeCommit(List<String> blockedExtensions)
+  private RevCommit makeCommit(RevWalk rw, List<String> blockedExtensions)
       throws NoFilepatternException, IOException, GitAPIException {
     Set<File> files = new HashSet<>();
     for (String extension : blockedExtensions) {
@@ -49,33 +50,37 @@
     files.add(new File(repo.getDirectory().getParent(), "foo.core.tmp"));
     files.add(new File(repo.getDirectory().getParent(), "foo.c"));
     files.add(new File(repo.getDirectory().getParent(), "foo.txt"));
-    return TestUtils.makeCommit(repo, "Commit with empty test files.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit with empty test files.", files);
   }
 
   @Test
   public void testBlockedExtensions() throws Exception {
-    RevCommit c = makeCommit(BLOCKED_EXTENSIONS_LC);
-    List<CommitValidationMessage> m = FileExtensionValidator
-        .performValidation(repo, c, BLOCKED_EXTENSIONS_LC);
-    List<String> expected = new ArrayList<>();
-    for (String extension : BLOCKED_EXTENSIONS_LC) {
-      expected.add("ERROR: blocked file: foo." + extension);
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommit(rw, BLOCKED_EXTENSIONS_LC);
+      List<CommitValidationMessage> m = FileExtensionValidator
+          .performValidation(repo, c, rw, BLOCKED_EXTENSIONS_LC);
+      List<String> expected = new ArrayList<>();
+      for (String extension : BLOCKED_EXTENSIONS_LC) {
+        expected.add("ERROR: blocked file: foo." + extension);
+      }
+      assertThat(TestUtils.transformMessages(m))
+          .containsExactlyElementsIn(expected);
     }
-    assertThat(TestUtils.transformMessages(m))
-        .containsExactlyElementsIn(expected);
   }
 
   @Test
   public void testBlockedExtensionsCaseInsensitive() throws Exception {
-    RevCommit c = makeCommit(BLOCKED_EXTENSIONS_UC);
-    List<CommitValidationMessage> m = FileExtensionValidator
-        .performValidation(repo, c, BLOCKED_EXTENSIONS_LC);
-    List<String> expected = new ArrayList<>();
-    for (String extension : BLOCKED_EXTENSIONS_UC) {
-      expected.add("ERROR: blocked file: foo." + extension);
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommit(rw, BLOCKED_EXTENSIONS_UC);
+      List<CommitValidationMessage> m = FileExtensionValidator
+          .performValidation(repo, c, rw, BLOCKED_EXTENSIONS_LC);
+      List<String> expected = new ArrayList<>();
+      for (String extension : BLOCKED_EXTENSIONS_UC) {
+        expected.add("ERROR: blocked file: foo." + extension);
+      }
+      assertThat(TestUtils.transformMessages(m))
+          .containsExactlyElementsIn(expected);
     }
-    assertThat(TestUtils.transformMessages(m))
-        .containsExactlyElementsIn(expected);
   }
 
   @Test
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidFilenameValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidFilenameValidatorTest.java
index a620824..6b5191a 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidFilenameValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidFilenameValidatorTest.java
@@ -21,6 +21,7 @@
 
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.junit.Test;
 
 import java.io.File;
@@ -42,28 +43,30 @@
     return filenames;
   }
 
-  private RevCommit makeCommit() throws IOException, GitAPIException {
+  private RevCommit makeCommit(RevWalk rw) throws IOException, GitAPIException {
     Set<File> files = new HashSet<>();
     for (String filenames : getInvalidFilenames()) {
       files.add(new File(repo.getDirectory().getParent(), filenames));
     }
     // valid filename
     files.add(new File(repo.getDirectory().getParent(), "test"));
-    return TestUtils.makeCommit(repo, "Commit with empty test files.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit with empty test files.", files);
   }
 
   @Test
   public void test() throws Exception {
     String[] invalidFilenamePattern = {"\\[|\\]|\\*|#", "[%:@]"};
-    RevCommit c = makeCommit();
-    List<CommitValidationMessage> m = InvalidFilenameValidator
-        .performValidation(repo, c, invalidFilenamePattern);
-    Set<String> expected = new HashSet<>();
-    for (String filenames : getInvalidFilenames()) {
-      expected.add("ERROR: invalid characters found in filename: " + filenames);
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommit(rw);
+      List<CommitValidationMessage> m = InvalidFilenameValidator
+          .performValidation(repo, c, rw, invalidFilenamePattern);
+      Set<String> expected = new HashSet<>();
+      for (String filenames : getInvalidFilenames()) {
+        expected.add("ERROR: invalid characters found in filename: " + filenames);
+      }
+      assertThat(TestUtils.transformMessages(m))
+          .containsExactlyElementsIn(expected);
     }
-    assertThat(TestUtils.transformMessages(m))
-        .containsExactlyElementsIn(expected);
   }
 
   @Test
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidLineEndingValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidLineEndingValidatorTest.java
index 9c3505e..664bcb8 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidLineEndingValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/InvalidLineEndingValidatorTest.java
@@ -22,6 +22,7 @@
 
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.junit.Test;
 
 import java.io.File;
@@ -32,7 +33,7 @@
 import java.util.Map;
 
 public class InvalidLineEndingValidatorTest extends ValidatorTestCase {
-  private RevCommit makeCommit() throws IOException, GitAPIException {
+  private RevCommit makeCommit(RevWalk rw) throws IOException, GitAPIException {
     Map<File, byte[]> files = new HashMap<>();
     // invalid line endings
     String content = "Testline1\r\n"
@@ -49,18 +50,20 @@
         + "Testline4";
     files.put(new File(repo.getDirectory().getParent(), "bar.txt"),
         content.getBytes(StandardCharsets.UTF_8));
-    return TestUtils.makeCommit(repo, "Commit with test files.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit with test files.", files);
   }
 
   @Test
   public void testCarriageReturn() throws Exception {
-    RevCommit c = makeCommit();
-    InvalidLineEndingValidator validator = new InvalidLineEndingValidator(null,
-        new ContentTypeUtil(PATTERN_CACHE), null, null, null);
-    List<CommitValidationMessage> m = validator.performValidation(repo, c,
-        EMPTY_PLUGIN_CONFIG);
-    assertThat(TestUtils.transformMessages(m)).containsExactly(
-        "ERROR: found carriage return (CR) character in file: foo.txt");
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommit(rw);
+      InvalidLineEndingValidator validator = new InvalidLineEndingValidator(null,
+          new ContentTypeUtil(PATTERN_CACHE), null, null, null);
+      List<CommitValidationMessage> m = validator.performValidation(repo, c,
+          rw, EMPTY_PLUGIN_CONFIG);
+      assertThat(TestUtils.transformMessages(m)).containsExactly(
+          "ERROR: found carriage return (CR) character in file: foo.txt");
+    }
   }
 
   @Test
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/MaxPathLengthValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/MaxPathLengthValidatorTest.java
index 4ce9dba..16f73d6 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/MaxPathLengthValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/MaxPathLengthValidatorTest.java
@@ -23,6 +23,7 @@
 import org.eclipse.jgit.api.Git;
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.junit.Test;
 
 import java.io.File;
@@ -39,36 +40,42 @@
     return (TOO_LONG.length() + GOOD.length()) / 2;
   }
 
-  private RevCommit makeCommit() throws IOException, GitAPIException {
+  private RevCommit makeCommit(RevWalk rw) throws IOException, GitAPIException {
     Set<File> files = new HashSet<>();
     files.add(TestUtils.createEmptyFile(TOO_LONG, repo));
     files.add(TestUtils.createEmptyFile(GOOD, repo));
-    return TestUtils.makeCommit(repo, "Commit with empty test files.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit with empty test files.", files);
   }
 
   @Test
   public void testAddTooLongPath() throws Exception {
-    RevCommit c = makeCommit();
-    List<CommitValidationMessage> m =
-        MaxPathLengthValidator.performValidation(repo, c, getMaxPathLength());
-    Set<String> expected =
-        ImmutableSet.of("ERROR: path too long: " + TOO_LONG);
-    assertThat(TestUtils.transformMessages(m))
-        .containsExactlyElementsIn(expected);
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommit(rw);
+      List<CommitValidationMessage> m =
+          MaxPathLengthValidator.performValidation(repo, c, rw,
+              getMaxPathLength());
+      Set<String> expected =
+          ImmutableSet.of("ERROR: path too long: " + TOO_LONG);
+      assertThat(TestUtils.transformMessages(m))
+          .containsExactlyElementsIn(expected);
+    }
   }
 
   @Test
   public void testDeleteTooLongPath() throws Exception {
-    RevCommit c = makeCommit();
-    try(Git git = new Git(repo)) {
-      Set<File> files = new HashSet<>();
-      files.add(TestUtils.createEmptyFile(TOO_LONG, repo));
-      TestUtils.removeFiles(git, files);
-      c = git.commit().setMessage("Delete file which is too long").call();
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommit(rw);
+      try(Git git = new Git(repo)) {
+        Set<File> files = new HashSet<>();
+        files.add(TestUtils.createEmptyFile(TOO_LONG, repo));
+        TestUtils.removeFiles(git, files);
+        c = git.commit().setMessage("Delete file which is too long").call();
+        rw.parseCommit(c);
+      }
+      List<CommitValidationMessage> m = MaxPathLengthValidator
+          .performValidation(repo, c, rw, getMaxPathLength());
+      assertThat(m).isEmpty();
     }
-    List<CommitValidationMessage> m = MaxPathLengthValidator
-        .performValidation(repo, c, getMaxPathLength());
-    assertThat(m).isEmpty();
   }
 
   @Test
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/SubmoduleValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/SubmoduleValidatorTest.java
index d24b3c2..4f867a7 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/SubmoduleValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/SubmoduleValidatorTest.java
@@ -23,6 +23,7 @@
 import org.eclipse.jgit.api.SubmoduleAddCommand;
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.junit.Test;
 
 import java.io.File;
@@ -32,7 +33,7 @@
 import java.util.Map;
 
 public class SubmoduleValidatorTest extends ValidatorTestCase {
-  private RevCommit makeCommitWithSubmodule()
+  private RevCommit makeCommitWithSubmodule(RevWalk rw)
       throws IOException, GitAPIException {
     try (Git git = new Git(repo)) {
       SubmoduleAddCommand addCommand = git.submoduleAdd();
@@ -40,32 +41,36 @@
       addCommand.setPath("modules/library");
       addCommand.call().close();
       git.add().addFilepattern(".").call();
-      return git.commit().setMessage("Commit with submodule.").call();
+      return rw.parseCommit(git.commit().setMessage("Commit with submodule.").call());
     }
   }
 
   @Test
   public void testWithSubmodule() throws Exception {
-    RevCommit c = makeCommitWithSubmodule();
-    List<CommitValidationMessage> m =
-        SubmoduleValidator.performValidation(repo, c);
-    assertThat(TestUtils.transformMessages(m))
-        .containsExactly("ERROR: submodules are not allowed: modules/library");
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommitWithSubmodule(rw);
+      List<CommitValidationMessage> m =
+          SubmoduleValidator.performValidation(repo, c, rw);
+      assertThat(TestUtils.transformMessages(m))
+          .containsExactly("ERROR: submodules are not allowed: modules/library");
+    }
   }
 
-  private RevCommit makeCommitWithoutSubmodule()
+  private RevCommit makeCommitWithoutSubmodule(RevWalk rw)
       throws IOException, GitAPIException {
     Map<File, byte[]> files = new HashMap<>();
     files.put(new File(repo.getDirectory().getParent(), "foo.txt"), null);
-    return TestUtils.makeCommit(repo, "Commit with empty test files.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit with empty test files.", files);
   }
 
   @Test
   public void testWithoutSubmodule() throws Exception {
-    RevCommit c = makeCommitWithoutSubmodule();
-    List<CommitValidationMessage> m =
-        SubmoduleValidator.performValidation(repo, c);
-    assertThat(m).isEmpty();
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommitWithoutSubmodule(rw);
+      List<CommitValidationMessage> m =
+          SubmoduleValidator.performValidation(repo, c, rw);
+      assertThat(m).isEmpty();
+    }
   }
 
   @Test
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/SymlinkValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/SymlinkValidatorTest.java
index a4c2127..2e17c29 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/SymlinkValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/SymlinkValidatorTest.java
@@ -22,6 +22,7 @@
 
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.junit.Test;
 
 import java.io.File;
@@ -34,7 +35,7 @@
 import java.util.Set;
 
 public class SymlinkValidatorTest extends ValidatorTestCase {
-  private RevCommit makeCommitWithSymlink()
+  private RevCommit makeCommitWithSymlink(RevWalk rw)
       throws IOException, GitAPIException {
     Map<File, byte[]> files = new HashMap<>();
     File link = new File(repo.getDirectory().getParent(), "foo.txt");
@@ -45,34 +46,38 @@
     Files.createSymbolicLink(link.toPath(), Paths.get("folder"));
     files.put(link, null);
 
-    return TestUtils.makeCommit(repo, "Commit with symlink.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit with symlink.", files);
   }
 
   @Test
   public void testWithSymlink() throws Exception {
-    RevCommit c = makeCommitWithSymlink();
-    List<CommitValidationMessage> m =
-        SymlinkValidator.performValidation(repo, c);
-    Set<String> expected = ImmutableSet.of(
-        "ERROR: Symbolic links are not allowed: foo.txt",
-        "ERROR: Symbolic links are not allowed: symbolicFolder");
-    assertThat(TestUtils.transformMessages(m))
-        .containsExactlyElementsIn(expected);
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommitWithSymlink(rw);
+      List<CommitValidationMessage> m =
+          SymlinkValidator.performValidation(repo, rw.parseCommit(c), rw);
+      Set<String> expected = ImmutableSet.of(
+          "ERROR: Symbolic links are not allowed: foo.txt",
+          "ERROR: Symbolic links are not allowed: symbolicFolder");
+      assertThat(TestUtils.transformMessages(m))
+          .containsExactlyElementsIn(expected);
+    }
   }
 
-  private RevCommit makeCommitWithoutSymlink()
+  private RevCommit makeCommitWithoutSymlink(RevWalk rw)
       throws IOException, GitAPIException {
     Map<File, byte[]> files = new HashMap<>();
     files.put(new File(repo.getDirectory().getParent(), "foo.txt"), null);
-    return TestUtils.makeCommit(repo, "Commit with empty test files.", files);
+    return TestUtils.makeCommit(rw, repo, "Commit with empty test files.", files);
   }
 
   @Test
   public void testWithoutSymlink() throws Exception {
-    RevCommit c = makeCommitWithoutSymlink();
-    List<CommitValidationMessage> m =
-        SymlinkValidator.performValidation(repo, c);
-    assertThat(m).isEmpty();
+    try (RevWalk rw = new RevWalk(repo)) {
+      RevCommit c = makeCommitWithoutSymlink(rw);
+      List<CommitValidationMessage> m =
+          SymlinkValidator.performValidation(repo, rw.parseCommit(c), rw);
+      assertThat(m).isEmpty();
+    }
   }
 
   @Test
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/TestUtils.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/TestUtils.java
index ab17832..21d4f31 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/TestUtils.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/TestUtils.java
@@ -33,6 +33,7 @@
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevTree;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
 
 import java.io.File;
@@ -69,22 +70,22 @@
     return repository;
   }
 
-  public static RevCommit makeCommit(Repository repo, String message,
+  public static RevCommit makeCommit(RevWalk rw, Repository repo, String message,
       Set<File> files) throws IOException, GitAPIException {
     Map<File, byte[]> tmp = new HashMap<>();
     for (File f : files) {
       tmp.put(f, null);
     }
-    return makeCommit(repo, message, tmp);
+    return makeCommit(rw, repo, message, tmp);
   }
 
-  public static RevCommit makeCommit(Repository repo, String message,
+  public static RevCommit makeCommit(RevWalk rw, Repository repo, String message,
       Map<File, byte[]> files) throws IOException, GitAPIException {
     try (Git git = new Git(repo)) {
       if (files != null) {
         addFiles(git, files);
       }
-      return git.commit().setMessage(message).call();
+      return rw.parseCommit(git.commit().setMessage(message).call());
     }
   }
 
@@ -148,18 +149,18 @@
     return repo.file(pathname, repo.blob(content));
   }
 
-  public static RevCommit makeCommit(DirCacheEntry[] entries,
+  public static RevCommit makeCommit(RevWalk rw, DirCacheEntry[] entries,
       TestRepository<Repository> repo) throws Exception {
-    return makeCommit(entries, repo, (RevCommit[]) null);
+    return makeCommit(rw, entries, repo, (RevCommit[]) null);
   }
 
-  public static RevCommit makeCommit(DirCacheEntry[] entries,
+  public static RevCommit makeCommit(RevWalk rw, DirCacheEntry[] entries,
       TestRepository<Repository> repo, RevCommit... parents)
       throws Exception {
     final RevTree ta = repo.tree(entries);
     RevCommit c =
         (parents == null) ? repo.commit(ta) : repo.commit(ta, parents);
     repo.parseBody(c);
-    return c;
+    return rw.parseCommit(c);
   }
 }