Update pom.xml

Update mirror-maker OAUTH2 sample pom.xml to generate single assembly with dependencies.

tutorials/oauth/mirror-maker/pom.xml

@@ -45,6 +45,23 @@
           <encoding>UTF-8</encoding>
         </configuration>
       </plugin>
+      <plugin>
+          <artifactId>maven-assembly-plugin</artifactId>
+          <configuration>
+            <descriptorRefs>
+              <descriptorRef>jar-with-dependencies</descriptorRef>
+            </descriptorRefs>
+          </configuration>
+          <executions>
+            <execution>
+              <id>make-assembly</id> <!-- this is used for inheritance merges -->
+              <phase>package</phase> <!-- bind to the packaging phase -->
+              <goals>
+                <goal>single</goal>
+              </goals>
+            </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>