[MWAR-430] Discover Jakarta Servlet API as excuse for not having web.xml

- Use MWAR-396_servlet30 as IT for this issue
- Extract method to check for Servlet 3.0+
- Extract method to check for class
- Check for Jakarta annotation as well
- Require at least JDK8 to use jakarta servlet API

src/it/MWAR-430_jakarta-servlet/invoker.properties

@@ -0,0 +1,19 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+invoker.java.version = 1.8+
+

src/it/MWAR-430_jakarta-servlet/pom.xml

@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+<project>
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.apache.maven.its.war</groupId>
+  <artifactId>maven-it-mwar-430</artifactId>
+  <version>1.0</version>
+  <packaging>war</packaging>
+
+  <name>Maven Integration Test :: MWAR-430</name> 
+  <description>Test that no web.xml is required when project depends on Jakarta Servlet 5.0 or newer</description>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>jakarta.servlet</groupId>
+      <artifactId>jakarta.servlet-api</artifactId>
+      <version>5.0.0-M1</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>commons-logging</groupId>
+      <artifactId>commons-logging</artifactId>
+      <version>1.0.3</version>
+    </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>3.8.2</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-war-plugin</artifactId>
+        <version>@project.version@</version>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/it/MWAR-430_jakarta-servlet/verify.bsh

@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.io.*;
+import java.util.*;
+import java.util.jar.*;
+import java.util.regex.*;
+
+try
+{
+    File explodedDir = new File( basedir, "target/maven-it-mwar-430-1.0" );
+    System.out.println( "Checking for existence of exploded directory " + explodedDir );
+    if ( !explodedDir.exists() )
+    {
+        System.out.println( "FAILURE! The directory " + explodedDir + " does not exist." );
+        return false;
+    }
+
+    File webInfFile = new File( explodedDir, "WEB-INF/web.xml" );
+    if ( webInfFile.exists() )
+    {
+        System.err.println( "FAILURE! The file web.xml should not be present." );
+        return false;
+    }
+
+}
+catch( Throwable t )
+{
+    t.printStackTrace();
+    return false;
+}
+
+return true;

src/main/java/org/apache/maven/plugins/war/WarMojo.java

@@ -301,13 +301,16 @@ else if ( artifact.getFile() == null || artifact.getFile().isDirectory() )
     }
 
     /**
-     * Determines if the current Maven project being built uses the Servlet 3.0 API (JSR 315). If it does then the
-     * <code>web.xml</code> file can be omitted.
+     * Determines if the current Maven project being built uses the Servlet 3.0 API (JSR 315)
+     * or Jakarta Servlet API.
+     * If it does then the <code>web.xml</code> file can be omitted.
      * <p>
-     * This is done by checking if the interface <code>javax.servlet.annotation.WebServlet</code> is in the compile-time
+     * This is done by checking if the interface <code>javax.servlet.annotation.WebServlet</code>
+     * or <code>jakarta.servlet.annotation.WebServlet</code> is in the compile-time
      * dependencies (which includes provided dependencies) of the Maven project.
      *
-     * @return <code>true</code> if the project being built depends on Servlet 3.0 API, <code>false</code> otherwise.
+     * @return <code>true</code> if the project being built depends on Servlet 3.0 API or Jakarta Servlet API,
+     *         <code>false</code> otherwise.
      * @throws DependencyResolutionRequiredException if the compile elements can't be resolved.
      * @throws MalformedURLException if the path to a dependency file can't be transformed to a URL.
      */
@@ -321,9 +324,21 @@ private boolean isProjectUsingAtLeastServlet30()
             urls[i] = new File( classpathElements.get( i ) ).toURI().toURL();
         }
         ClassLoader loader = new URLClassLoader( urls, Thread.currentThread().getContextClassLoader() );
+
+        return hasWebServletAnnotationClassInClasspath( loader );
+    }
+
+    private static boolean hasWebServletAnnotationClassInClasspath( ClassLoader loader )
+    {
+        return hasClassInClasspath( loader, "javax.servlet.annotation.WebServlet" )
+                || hasClassInClasspath( loader, "jakarta.servlet.annotation.WebServlet" );
+    }
+
+    private static boolean hasClassInClasspath( ClassLoader loader, String clazz )
+    {
         try
         {
-            Class.forName( "javax.servlet.annotation.WebServlet", false, loader );
+            Class.forName( clazz, false, loader );
             return true;
         }
         catch ( ClassNotFoundException e )