Issue #3471: Fix order of "default" method modifier

src/it/java/com/google/checkstyle/test/chapter4formatting/rule487modifiers/ModifierOrderTest.java

@@ -97,6 +97,7 @@ public class ModifierOrderTest extends BaseCheckTestSupport {
             "215:28: " + getCheckMessage(clazz, msgMod, "synchronized"),
             "217:37: " + getCheckMessage(clazz, msgMod, "protected"),
             "219:22: " + getCheckMessage(clazz, msgAnnotation, "@MyAnnotation2"),
+            "245:14: " + getCheckMessage(clazz, msgMod, "default"),
         };
 
         final Configuration checkConfig = getCheckConfig("ModifierOrder");

src/it/resources/com/google/checkstyle/test/chapter4formatting/rule487modifiers/InputModifierOrder.java

@@ -236,3 +236,11 @@ class WithInner
 
 @interface MyAnnotation4 {
 }
+
+/** Illegal order of modifiers for interface methods */
+interface InputModifierOrderInterface
+{
+    default strictfp void a() { }  //ok
+
+    strictfp default void b() { }  //warn
+}

src/main/java/com/puppycrawl/tools/checkstyle/checks/modifier/ModifierOrderCheck.java

@@ -41,6 +41,7 @@ import com.puppycrawl.tools.checkstyle.api.TokenTypes;
 
   <li><span class="code">private</span></li>
   <li><span class="code">abstract</span></li>
+  <li><span class="code">default</span></li>
   <li><span class="code">static</span></li>
   <li><span class="code">final</span></li>
   <li><span class="code">transient</span></li>
@@ -84,8 +85,8 @@ public class ModifierOrderCheck
      * 8.3.1 and 8.4.3 of the JLS.
      */
     private static final String[] JLS_ORDER = {
-        "public", "protected", "private", "abstract", "static", "final",
-        "transient", "volatile", "synchronized", "native", "strictfp", "default",
+        "public", "protected", "private", "abstract", "default", "static",
+        "final", "transient", "volatile", "synchronized", "native", "strictfp",
     };
 
     @Override

src/test/java/com/puppycrawl/tools/checkstyle/checks/modifier/ModifierOrderCheckTest.java

@@ -66,6 +66,7 @@ public class ModifierOrderCheckTest
             "34:13: " + getCheckMessage(MSG_ANNOTATION_ORDER, "@MyAnnotation2"),
             "39:13: " + getCheckMessage(MSG_ANNOTATION_ORDER, "@MyAnnotation2"),
             "49:35: " + getCheckMessage(MSG_ANNOTATION_ORDER, "@MyAnnotation4"),
+            "157:14: " + getCheckMessage(MSG_MODIFIER_ORDER, "default"),
         };
         verify(checkConfig, getPath("InputModifier.java"), expected);
     }

src/test/resources/com/puppycrawl/tools/checkstyle/checks/modifier/InputModifier.java

@@ -143,4 +143,18 @@ enum TestEnum {
     
     public void method() {
     }
-}
+}
+
+/** holder for interface specific modifier check. */
+interface InputDefaultPublicModifier
+{
+    /** correct order */
+    default strictfp void a()
+    {
+    }
+
+    /** wrong order */
+    strictfp default void b() // violation
+    {
+    }
+}

src/xdocs/config_modifier.xml

@@ -27,8 +27,9 @@
           Checks that the order of modifiers conforms to the suggestions in
           the <a
           href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-8.html">Java
-          Language specification, sections 8.1.1, 8.3.1 and 8.4.3</a>. The
-          correct order is:
+          Language specification, sections 8.1.1, 8.3.1, 8.4.3</a> and <a
+          href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-9.html">
+          9.4</a>. The correct order is:
         </p>
 
         <ol>
@@ -44,6 +45,9 @@
           <li>
             <code>abstract</code>
           </li>
+          <li>
+            <code>default</code>
+          </li>
           <li>
             <code>static</code>
           </li>