IDEA-168633 Warn if variable of type java.util.Optional is initialized with null

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/optionalNull/afterOptionalNull.java

@@ -0,0 +1,27 @@
+// "Fix all 'Null value for Optional type' problems in file" "true"
+import java.util.List;
+import java.util.Optional;
+import java.util.OptionalInt;
+
+public class Test {
+  Optional<String> field = Optional.empty();
+  Optional<? extends CharSequence> field2 = Optional.empty();
+
+  public <T> void test(List<T> list) {
+    Optional<T> s = list.size() > 0 ? Optional.of(list.get(0)) : Optional.empty();
+    varArg(1, Optional.of(1), Optional.empty());
+    m((Optional<String>) Optional.<String>empty());
+    Optional.of("xyz").flatMap(x -> Optional.empty()).ifPresent(System.out::println);
+  }
+
+  OptionalInt opt() {
+    return OptionalInt.empty();
+  }
+
+  void m(Optional<String> opt) {}
+  void m(String s) {}
+
+  void varArg(int x, Optional<?>... opts) {
+
+  };
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/optionalNull/beforeOptionalNull.java

@@ -0,0 +1,27 @@
+// "Fix all 'Null value for Optional type' problems in file" "true"
+import java.util.List;
+import java.util.Optional;
+import java.util.OptionalInt;
+
+public class Test {
+  Optional<String> field = null;
+  Optional<? extends CharSequence> field2 = null;
+
+  public <T> void test(List<T> list) {
+    Optional<T> s = list.size() > 0 ? Optional.of(list.get(0)) : n<caret>ull;
+    varArg(1, Optional.of(1), null);
+    m((Optional<String>) null);
+    Optional.of("xyz").flatMap(x -> null).ifPresent(System.out::println);
+  }
+
+  OptionalInt opt() {
+    return null;
+  }
+
+  void m(Optional<String> opt) {}
+  void m(String s) {}
+
+  void varArg(int x, Optional<?>... opts) {
+
+  };
+}