HADOOP-19298. [JDK17] Add a JDK17 profile. (#7085) Contributed by Shilun Fan.

Reviewed-by: Steve Loughran <stevel@apache.org>
Reviewed-by: Attila Doroszlai <adoroszlai@apache.org>
Reviewed-by: Cheng Pan <chengpan@apache.org>
Reviewed-by: Min Yan <yaommen@gmail.com>
Signed-off-by: Shilun Fan <slfan1989@apache.org>

hadoop-project/pom.xml

@@ -2754,6 +2754,16 @@
         </dependencies>
       </dependencyManagement>
     </profile>
+    <!-- We added this profile to support compilation for JDK 9 and above. -->
+    <profile>
+      <id>java9</id>
+      <activation>
+        <jdk>[9,)</jdk>
+      </activation>
+      <properties>
+        <maven.compiler.release>${javac.version}</maven.compiler.release>
+      </properties>
+    </profile>
   </profiles>
 
   <repositories>