method call should always flush fields (IDEA-93168)

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

@@ -0,0 +1,21 @@
+import org.jetbrains.annotations.Nullable;
+
+class Fun {
+  @Nullable
+  private Object foo;
+
+  public Fun() {
+    foo = new Object();
+    makeMagic();
+
+    if (null == foo) {
+      System.out.println("hello");
+    }
+
+  }
+
+  private void makeMagic() {
+    foo = null;
+  }
+
+}