Add verify that checks license is present in all generated files

modello-maven-plugin/src/it/maven-model/verify.groovy

@@ -0,0 +1,32 @@
+/*
+ * 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.
+ */
+
+File generatedSources = new File(basedir, "target/generated-sources/modello")
+File generatedSite = new File(basedir, "target/generated-site/resources/xsd")
+assert generatedSources.exists()
+assert generatedSources.isDirectory()
+assert generatedSite.exists()
+assert generatedSite.isDirectory()
+
+String javaSource = new File(generatedSources, "org/apache/maven/model/Model.java").text
+String xsdSource = new File(generatedSite, "maven-4.0.0.xsd").text
+
+// due formatting issues (empty lines lost) let's stick with trivial license and assertion for now
+assert javaSource.contains("The license of this file")
+assert xsdSource.contains("The license of this file")