Prepare for release

build.gradle

@@ -65,8 +65,8 @@ subprojects {
   group = 'com.github.ben-manes.caffeine'
   version.with {
     major = 2 // incompatible API changes
-    minor = 3 // backwards-compatible additions
-    patch = 6 // backwards-compatible bug fixes
+    minor = 4 // backwards-compatible additions
+    patch = 0 // backwards-compatible bug fixes
     releaseBuild = rootProject.hasProperty('release')
   }
   archivesBaseName = path[1..-1].replaceAll(':', '-').toLowerCase()

guava/src/test/java/com/google/common/cache/CacheBuilderTest.java

@@ -391,7 +391,7 @@ public void testRemovalNotification_clear() throws InterruptedException {
    * cache afterward).
    */
   @GwtIncompatible("QueuingRemovalListener")
-
+  @SuppressWarnings("FutureReturnValueIgnored")
   public void testRemovalNotification_clear_basher() throws InterruptedException {
     // If a clear() happens close to the end of computation, one of two things should happen:
     // - computation ends first: the removal listener is called, and the cache does not contain the
@@ -468,6 +468,7 @@ public void testRemovalNotification_clear_basher() throws InterruptedException {
    * (removed because of size limits or expiration) trigger appropriate removal notifications.
    */
   @GwtIncompatible("QueuingRemovalListener")
+  @SuppressWarnings("FutureReturnValueIgnored")
   // FIXME(ben): disabled due to TravisCI killing the process
   public void testRemovalNotification_get_basher() throws InterruptedException {
     int nTasks = 1000;

jcache/src/test/java/com/github/benmanes/caffeine/jcache/JCacheProfiler.java

@@ -77,6 +77,7 @@ public void start() {
     }
   }
 
+  @SuppressWarnings("FutureReturnValueIgnored")
   private void scheduleStatusTask() {
     Stopwatch stopwatch = Stopwatch.createStarted();
     Executors.newSingleThreadScheduledExecutor().scheduleWithFixedDelay(() -> {