travis: also build with java 9
diff --git a/.travis.yml b/.travis.yml
index c1335bd..8893f59 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,6 +19,7 @@
 jdk:
   - openjdk7
   - oraclejdk8
+  - oraclejdk9
 
 after_success:
   - mvn clean cobertura:cobertura coveralls:report
diff --git a/pom.xml b/pom.xml
index 867f9e8..ee13cd8 100644
--- a/pom.xml
+++ b/pom.xml
@@ -483,5 +483,15 @@
         </plugins>
       </build>
     </profile>
+    <profile>
+      <id>java9</id>
+      <activation>
+        <jdk>9</jdk>
+      </activation>
+      <properties>
+        <!-- coverall version 4.3.0 does not work with java 9, see https://github.com/trautonen/coveralls-maven-plugin/issues/112 -->
+        <coveralls.skip>true</coveralls.skip>
+      </properties>
+    </profile>
   </profiles>
 </project>