QPIDJMS-497: add maven.compiler.release config when building with JDK9+
diff --git a/pom.xml b/pom.xml
index 446b788..e25ed7a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -35,9 +35,6 @@
   </description>
 
   <properties>
-    <maven.compiler.source>1.8</maven.compiler.source>
-    <maven.compiler.target>1.8</maven.compiler.target>
-
     <!-- Dependency Versions for this Project -->
     <proton-version>0.33.4</proton-version>
     <netty-version>4.1.48.Final</netty-version>
@@ -66,6 +63,10 @@
     <jacoco-plugin-version>0.8.5</jacoco-plugin-version>
     <surefire.version>2.22.2</surefire.version>
 
+    <!-- See also maven.compiler.release in the java9on profile -->
+    <maven.compiler.source>1.8</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
+
     <!-- Test properties -->
     <maven.test.redirectTestOutputToFile>true</maven.test.redirectTestOutputToFile>
     <surefire.runOrder>filesystem</surefire.runOrder>
@@ -378,6 +379,16 @@
     </profile>
 
     <profile>
+      <id>java9on</id>
+      <activation>
+        <jdk>[9,)</jdk>
+      </activation>
+      <properties>
+        <maven.compiler.release>8</maven.compiler.release>
+      </properties>
+    </profile>
+
+    <profile>
       <id>java11on</id>
       <activation>
         <jdk>[11,)</jdk>