java 9: ensure private methods in interfaces do not receive implicit public modifier (IDEA-171089)

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

@@ -0,0 +1,25 @@
+interface A {
+  void m();
+}
+interface A1 extends A {
+  <error descr="Static method 'm()' in 'A1' cannot override instance method 'm()' in 'A'">private static void m()</error> {}
+}
+interface A2 extends A {
+  <error descr="'m()' in 'A2' clashes with 'm()' in 'A'; attempting to assign weaker access privileges ('private'); was 'public'">private</error> void m() {}
+}
+
+interface B {
+  private void m() {}
+}
+interface B1 extends B {
+  private void m() {}
+}
+interface B2 extends B {
+  private static void m() {}
+}
+interface B3 extends B {
+  default void m() {}
+}
+interface B4 extends B {
+  void m();
+}