Ignore JDK9 "module-info" class file by default.

Suggested by @bclozel in #31

src/it/test-issue-31/invoker.properties

@@ -0,0 +1,16 @@
+#
+# Licensed 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.goals=clean verify
+invoker.buildResult = success

src/it/test-issue-31/pom.xml

@@ -0,0 +1,48 @@
+<!--
+~   Licensed 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 xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>@project.groupId@.@project.artifactId@</groupId>
+        <artifactId>basepom</artifactId>
+        <version>1.0.under-test</version>
+    </parent>
+
+    <artifactId>test-issue-31</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.ow2.asm</groupId>
+            <artifactId>asm</artifactId>
+            <version>6.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.ow2.asm</groupId>
+            <artifactId>asm-analysis</artifactId>
+            <version>6.0</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>@project.groupId@</groupId>
+                <artifactId>@project.artifactId@</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>

src/it/test-issue-31/verify.groovy

@@ -0,0 +1,20 @@
+/*
+ * Licensed 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 static org.basepom.mojo.duplicatefinder.groovy.ITools.*
+
+def (result, xml) = loadXmlAndResult(basedir, "test")
+
+overallState(NO_CONFLICT, 0, NOT_FAILED, result)
+
+return true

src/main/java/org/basepom/mojo/duplicatefinder/classpath/ClasspathDescriptor.java

@@ -74,7 +74,8 @@ public class ClasspathDescriptor
 
     private static final MatchPatternPredicate DEFAULT_IGNORED_CLASS_PREDICATE = new MatchPatternPredicate(Arrays.asList(
         // this regex matches inner classes
-        ".*\\$.*"));
+        ".*\\$.*",
+        "module-info"));
 
     private static final MatchPatternPredicate DEFAULT_IGNORED_LOCAL_DIRECTORIES = new MatchPatternPredicate(Arrays.asList(
         "^.git$",