forbid private classes in java 9 interfaces (IDEA-167121)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting9/PrivateInInterfaces.java

@@ -12,4 +12,12 @@ interface C {
 
 interface D {
     private static void m() {}
+}
+
+interface E {
+    <error descr="Illegal combination of modifiers: 'private' and 'public'">private</error> class E1 {}
+}
+
+interface F {
+    <error descr="Modifier 'private' not allowed here">private</error> int m = 0;
 }