when a nullable variable is assigned with an unknown value, don't consider it nullable (IDEA-42890)

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

@@ -267,7 +267,10 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
     if (var == value) return;
 
     flushVariable(var);
-    if (value instanceof DfaUnknownValue) return;
+    if (value instanceof DfaUnknownValue) {
+      getVariableState(var).setNullable(false);
+      return;
+    }
 
     getVariableState(var).setValue(value);
     if (value instanceof DfaNotNullValue) {

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

@@ -0,0 +1,14 @@
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class BrokenAlignment {
+
+  public void main(String... args) {
+    @Nullable Class object = Object.class;
+    output2(object);
+  }
+
+  public static void output2(@NotNull Object value) {
+    System.out.println(value);
+  }
+}

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

@@ -84,6 +84,7 @@ public class DataFlowInspectionFixtureTest extends JavaCodeInsightFixtureTestCas
   public void testChainedFinalFieldAccessorsDfa() throws Throwable { doTest(); }
 
   public void testAssigningUnknownToNullable() throws Throwable { doTest(); }
+  public void testAssigningClassLiteralToNullable() throws Throwable { doTest(); }
 
   public void testSynchronizingOnNullable() throws Throwable { doTest(); }
   public void testReturningNullFromVoidMethod() throws Throwable { doTest(); }