Interface methods can be private now

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/ast/ASTMethodDeclaration.java

@@ -57,7 +57,8 @@ public class ASTMethodDeclaration extends AbstractJavaAccessNode implements DFAG
 
     @Override
     public boolean isPublic() {
-        if (isInterfaceMember()) {
+        // interface methods are public by default, but could be private since java9
+        if (isInterfaceMember() && !isPrivate()) {
             return true;
         }
         return super.isPublic();

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/ast/ASTMethodDeclarationTest.java

@@ -5,9 +5,13 @@
 package net.sourceforge.pmd.lang.java.ast;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 import org.junit.Test;
 
+import net.sourceforge.pmd.lang.java.ParserTstUtil;
+
 public class ASTMethodDeclarationTest {
 
     @Test
@@ -21,4 +25,20 @@ public class ASTMethodDeclarationTest {
 
         assertEquals("foo", md.getMethodName());
     }
+
+    @Test
+    public void testPrivateInterfaceMethods() {
+        ASTCompilationUnit node = ParserTstUtil.parseJava9("public interface Foo { private void bar() { } }");
+        ASTMethodDeclaration methodDecl = node.getFirstDescendantOfType(ASTMethodDeclaration.class);
+        assertTrue(methodDecl.isPrivate());
+        assertFalse(methodDecl.isPublic());
+    }
+
+    @Test
+    public void testPublicInterfaceMethods() {
+        ASTCompilationUnit node = ParserTstUtil.parseJava9("public interface Foo { void bar(); }");
+        ASTMethodDeclaration methodDecl = node.getFirstDescendantOfType(ASTMethodDeclaration.class);
+        assertFalse(methodDecl.isPrivate());
+        assertTrue(methodDecl.isPublic());
+    }
 }