Merge branch 'stable-3.2' into stable-3.3

* stable-3.2:
  Bazel: Consume bazel-toolchains release from bazel mirror
  Align the recommended buildifier version with CI's
  crafting-changes: Add some info on Optional/Nullable
  Bump bazel-toolchains to 5.0.0
  Set version to 2.16.28-SNAPSHOT
  Set version to 2.16.27
  ForRef#check should permit internal users to read all refs
  Fix NPE on trying to send email for user without email address
  Update git submodules
  Update highlightjs to 10.6.0
  Use NoteDb sequence seed for groups sequence initialization
  GroupsOnInit: Remove unused dependency on ReviewDb
  Use NoteDb sequence seed for accounts sequence initialization
  Do not use ReviewDb anymore when is disabled
  Elasticsearch: Discontinue EOL versions 7.2 and 7.3 support
  e2e-tests: Add SubmitChangeInBranch scenario
  Update developers based on gerritcodereview's list
  ForRef#check should permit internal users to read all refs

Change-Id: I91c6be1bee77f4a56cd851281b5ccee918cbd2e5
diff --git a/java/com/google/gerrit/elasticsearch/ElasticVersion.java b/java/com/google/gerrit/elasticsearch/ElasticVersion.java
index bba1577..5e72780 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticVersion.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticVersion.java
@@ -18,8 +18,6 @@
 import java.util.regex.Pattern;
 
 public enum ElasticVersion {
-  V7_2("7.2.*"),
-  V7_3("7.3.*"),
   V7_4("7.4.*"),
   V7_5("7.5.*"),
   V7_6("7.6.*"),
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java b/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
index e8cf3e9..8cd09e6 100644
--- a/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
+++ b/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
@@ -39,10 +39,6 @@
 
   private static String getImageName(ElasticVersion version) {
     switch (version) {
-      case V7_2:
-        return "blacktop/elasticsearch:7.2.1";
-      case V7_3:
-        return "blacktop/elasticsearch:7.3.2";
       case V7_4:
         return "blacktop/elasticsearch:7.4.2";
       case V7_5:
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java b/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
index 1ec8a5d..508dc84 100644
--- a/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
+++ b/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
@@ -22,12 +22,6 @@
 public class ElasticVersionTest {
   @Test
   public void supportedVersion() throws Exception {
-    assertThat(ElasticVersion.forVersion("7.2.0")).isEqualTo(ElasticVersion.V7_2);
-    assertThat(ElasticVersion.forVersion("7.2.1")).isEqualTo(ElasticVersion.V7_2);
-
-    assertThat(ElasticVersion.forVersion("7.3.0")).isEqualTo(ElasticVersion.V7_3);
-    assertThat(ElasticVersion.forVersion("7.3.1")).isEqualTo(ElasticVersion.V7_3);
-
     assertThat(ElasticVersion.forVersion("7.4.0")).isEqualTo(ElasticVersion.V7_4);
     assertThat(ElasticVersion.forVersion("7.4.1")).isEqualTo(ElasticVersion.V7_4);