AJ-684: add 'maven-gpg-plugin' in pom.xml;

Author: chengyitian

pom.xml

@@ -168,6 +168,20 @@
 <!--                </executions>-->
 <!--                <inherited>false</inherited>-->
 <!--            </plugin>-->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-gpg-plugin</artifactId>
+                <version>1.6</version>
+                <executions>
+                    <execution>
+                        <id>sign-artifacts</id>
+                        <phase>verify</phase>
+                        <goals>
+                            <goal>sign</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.5.1</version>