mvn pom.xml change needed to compile xgboost jvm as a single file

xgboost_single_jar.diff

diff --git a/jvm-packages/xgboost4j-spark/pom.xml b/jvm-packages/xgboost4j-spark/pom.xml
index 601bad1..4e24a49 100644
--- a/jvm-packages/xgboost4j-spark/pom.xml
+++ b/jvm-packages/xgboost4j-spark/pom.xml
@@ -10,15 +10,25 @@
     </parent>
     <artifactId>xgboost4j-spark</artifactId>
     <build>
-        <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-assembly-plugin</artifactId>
-                <configuration>
-                    <skipAssembly>false</skipAssembly>
-                </configuration>
-            </plugin>
-        </plugins>
+     <plugins>
+      <!-- any other plugins -->
+      <plugin>
+        <artifactId>maven-assembly-plugin</artifactId>
+        <executions>
+          <execution>
+            <phase>package</phase>
+            <goals>
+              <goal>single</goal>
+            </goals>
+          </execution>
+        </executions>
+        <configuration>
+          <descriptorRefs>
+            <descriptorRef>jar-with-dependencies</descriptorRef>
+          </descriptorRefs>
+        </configuration>
+      </plugin>
+    </plugins>
     </build>
     <dependencies>
         <dependency>