Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  ChangeNotificationsIT: Fix eclipse warning(s) about static use
  CacheMetrics: Make F_NAME a final constant in class scope
  Fix more cases where Collection.isEmpty() should be used
  Use Set instead of EnumSet in method signatures
  Replace negation of anyMatch() with noneMatch()
  AllExternalIds: Replace lambdas with method references
  PostReview: Replace filter and findFirst with anyMatch
  XContentBuilder: Use UTF_8 from Java's StandardCharsets rather than Guava
  Update git submodules
  Update git submodules
  Update git submodules
  QueryDocumentationExecutor: Make WEIGHTS final and use ImmutableMap
  BooleanProjectConfigTransformations: Make MAPPER final
  TestSubmitRuleInfo: Make INSTANCE final
  TrackingFootersProvider: Make constants final
  ChangeCleanupConfig: Make constants final
  SetParent: Simplify lambda expression
  ProjectsConsistencyChecker: Simplify lambda expression
  Remove redundant null checks used with "instanceof"
  Remove unnecessary array creation for varargs parameters
  Remove redundant parentheses in lambda statements
  PreferencesBox: Remove unnecessary boxing to Boolean
  GitwebServlet: Rename bufferSize to BUFFER_SIZE and make static
  GetPatch: Make FILE_NOT_FOUND static
  DeleteZombieCommentsRefs: Make constants static
  AbstractNotificationTest: Make constants static and rename
  TabFile: Make TRIM final
  Remove redundant calls to toString()
  OpenIdServiceImpl: Fix incorrect null comparison of Optional
  Consistently use isEmpty to check for empty collection
  PageLinks: Reuse ADMIN_PROJECTS constant
  PageLinks: Fix typo in method name
  FlushCaches: Use isEmpty to check for empty list
  JGitMetricModule: Replace anonymous Supplier instances with method references
  Adapt to deprecation of WindowCacheStats methods in JGit
  Documentation: Fix collapsed words and broken link

Change-Id: I136c109013a8947ba530a52164e97af2775fe490

java/com/google/gerrit/mail/RawMailParser.java

@@ -69,7 +69,7 @@ public class RawMailParser {
     }
 
     // Add From, To and Cc
-    if (mimeMessage.getFrom() != null && mimeMessage.getFrom().size() > 0) {
+    if (mimeMessage.getFrom() != null && !mimeMessage.getFrom().isEmpty()) {
       Mailbox from = mimeMessage.getFrom().get(0);
       messageBuilder.from(new Address(from.getName(), from.getAddress()));
     }