IDEA-44118 Possible NPE from @Nullable isn't flagged in synchronized() statement

java/java-impl/src/com/intellij/codeInspection/dataFlow/ControlFlowAnalyzer.java

@@ -606,7 +606,7 @@ class ControlFlowAnalyzer extends JavaElementVisitor {
     PsiExpression lock = statement.getLockExpression();
     if (lock != null) {
       lock.accept(this);
-      addInstruction(new PopInstruction());
+      addInstruction(new FieldReferenceInstruction(lock, "Synchronized value"));
     }
 
     addInstruction(new FlushVariableInstruction(null));

java/java-tests/testData/inspection/dataFlow/fixture/SynchronizingOnNullable.java

@@ -0,0 +1,10 @@
+import org.jetbrains.annotations.Nullable;
+
+public class BrokenAlignment {
+
+  void test(@Nullable Object n) {
+    synchronized (<warning descr="Dereference of 'n' may produce 'java.lang.NullPointerException'">n</warning>) {
+
+    }
+  }
+}

java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionFixtureTest.java

@@ -85,4 +85,6 @@ public class DataFlowInspectionFixtureTest extends JavaCodeInsightFixtureTestCas
 
   public void testAssigningUnknownToNullable() throws Throwable { doTest(); }
 
+  public void testSynchronizingOnNullable() throws Throwable { doTest(); }
+
 }