Fix compilation warnings

Author: akarnokd

src/main/java/io/reactivex/internal/operators/completable/CompletableFromSource.java

@@ -38,6 +38,8 @@ static final class DisposeAwareCompletableObserver
     extends AtomicBoolean
     implements CompletableObserver, Disposable {
 
+        /** */
+        private static final long serialVersionUID = -1520879094105684863L;
         private final CompletableObserver o;
         private Disposable d;
 

src/main/java/io/reactivex/internal/operators/observable/ObservableFromSource.java

@@ -38,6 +38,8 @@ static final class DisposedAwareObserver<T>
     extends AtomicBoolean
     implements Observer<T>, Disposable {
 
+        /** */
+        private static final long serialVersionUID = -7920748056724379224L;
         private final Observer<? super T> o;
         private Disposable d;
 

src/main/java/io/reactivex/internal/operators/single/SingleFromSource.java

@@ -36,6 +36,8 @@ public SingleFromSource(SingleSource<T> source) {
     static final class DisposeAwareSingleObserver<T>
     extends AtomicBoolean
     implements SingleObserver<T>, Disposable {
+        /** */
+        private static final long serialVersionUID = -166991076349162358L;
         private final SingleObserver<? super T> o;
         private Disposable d;
 

src/test/java/io/reactivex/subscribers/SafeSubscriberWithPluginTest.java

@@ -13,7 +13,7 @@
 
 package io.reactivex.subscribers;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -55,7 +55,7 @@ public void onComplete() {
         SafeSubscriber<Integer> safe = new SafeSubscriber<Integer>(ts);
         try {
             safe.onComplete();
-            Assert.fail();
+            fail();
         } catch (RuntimeException e) {
             // FIXME no longer assertable
             // assertTrue(safe.isUnsubscribed());