SONAR-5970 Have tag changes appear in email notification

plugins/sonar-core-plugin/src/main/java/org/sonar/plugins/core/issue/notification/IssueChangesEmailTemplate.java

@@ -82,6 +82,15 @@ public class IssueChangesEmailTemplate extends EmailTemplate {
     appendField(sb, "Message", notif.getFieldValue("old.message"), notif.getFieldValue("new.message"));
     appendField(sb, "Author", notif.getFieldValue("old.author"), notif.getFieldValue("new.author"));
     appendFieldWithoutHistory(sb, "Action Plan", notif.getFieldValue("old.actionPlan"), notif.getFieldValue("new.actionPlan"));
+    appendField(sb, "Tags", formatTagChange(notif.getFieldValue("old.tags")), formatTagChange(notif.getFieldValue("new.tags")));
+  }
+
+  private static String formatTagChange(String tags) {
+    if (tags == null) {
+      return null;
+    } else {
+      return "[" + tags + "]";
+    }
   }
 
   private void appendHeader(Notification notif, StringBuilder sb) {

plugins/sonar-core-plugin/src/test/java/org/sonar/plugins/core/issue/notification/IssueChangesEmailTemplateTest.java

@@ -124,7 +124,8 @@ public class IssueChangesEmailTemplateTest {
       .setFieldValue("old.assignee", "simon")
       .setFieldValue("new.assignee", "louis")
       .setFieldValue("new.resolution", "FALSE-POSITIVE")
-      .setFieldValue("new.status", "RESOLVED");
+      .setFieldValue("new.status", "RESOLVED")
+      .setFieldValue("new.tags", "bug performance");
 
     EmailMessage email = template.format(notification);
     assertThat(email.getMessageId()).isEqualTo("issue-changes/ABCDE");

plugins/sonar-core-plugin/src/test/resources/org/sonar/plugins/core/issue/notification/IssueChangesEmailTemplateTest/email_with_multiple_changes.txt

@@ -6,5 +6,6 @@ Comment: How to fix it?
 Assignee changed to louis
 Resolution: FALSE-POSITIVE
 Status: RESOLVED
+Tags: [bug performance]
 
 See it in SonarQube: http://nemo.sonarsource.org/issues/search#issues=ABCDE