[WAGON-510] Upgrade parent to 31

Also resolve issues and todos which came along with version 31.
diff --git a/pom.xml b/pom.xml
index 865d3d2..cd129a8 100644
--- a/pom.xml
+++ b/pom.xml
@@ -21,9 +21,9 @@
   <modelVersion>4.0.0</modelVersion>
 
   <parent>
-    <artifactId>maven-parent</artifactId>
     <groupId>org.apache.maven</groupId>
-    <version>27</version>
+    <artifactId>maven-parent</artifactId>
+    <version>31</version>
     <relativePath>../pom/maven/pom.xml</relativePath>
   </parent>
 
@@ -340,13 +340,6 @@
             </systemPropertyVariables>
           </configuration>
         </plugin>
-        <plugin><!-- TODO remove when upgrading maven-parent to 25 -->
-          <groupId>org.apache.maven.plugins</groupId>
-          <artifactId>maven-site-plugin</artifactId>
-          <configuration>
-            <topSiteURL>scm:svn:https://svn.apache.org/repos/infra/websites/production/maven/components/${maven.site.path}</topSiteURL>
-          </configuration>
-        </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-javadoc-plugin</artifactId>
diff --git a/wagon-provider-test/src/main/java/org/apache/maven/wagon/http/HttpWagonTestCase.java b/wagon-provider-test/src/main/java/org/apache/maven/wagon/http/HttpWagonTestCase.java
index d24f78f..ee30271 100644
--- a/wagon-provider-test/src/main/java/org/apache/maven/wagon/http/HttpWagonTestCase.java
+++ b/wagon-provider-test/src/main/java/org/apache/maven/wagon/http/HttpWagonTestCase.java
@@ -1979,7 +1979,7 @@
 
         String transferEncoding;
 
-        public DeployedResource()
+        DeployedResource()
         {
             // no op
         }
@@ -2103,7 +2103,7 @@
 
         public List<HandlerRequestResponse> handlerRequestResponses = new ArrayList<HandlerRequestResponse>();
 
-        public TestHeaderHandler()
+        TestHeaderHandler()
         {
         }