IDEA-190727 Replace instanceof with null-check could automatically eliminate double negation

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/redundantInstanceOf/afterInstanceOfNegated.java

@@ -0,0 +1,10 @@
+// "Replace with a null check" "true"
+class Test {
+  void test(String s) {
+    Object obj = s;
+    if (obj == null) {
+      return;
+    }
+    System.out.println("always");
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/redundantInstanceOf/beforeInstanceOfNegated.java

@@ -0,0 +1,10 @@
+// "Replace with a null check" "true"
+class Test {
+  void test(String s) {
+    Object obj = s;
+    if (!(obj inst<caret>anceof String)) {
+      return;
+    }
+    System.out.println("always");
+  }
+}