Java: Take into account writes to the field done via AtomicFieldUpdater (IDEA-152262)

java/java-tests/testData/codeInsight/atomicReferenceImplicitUsage/LongGet.java

@@ -0,0 +1,11 @@
+import java.util.concurrent.atomic.AtomicLongFieldUpdater;
+
+class Atomics {
+  private volatile long <warning descr="Private field 'num' is never assigned">num</warning>;
+  private static final AtomicLongFieldUpdater<Atomics> updater =
+    AtomicLongFieldUpdater.newUpdater(Atomics.class, "num");
+
+  public long getLong() {
+    return updater.get(this);
+  }
+}