enabled PGP signing when using maven to perform a release.

gson/pom.xml

@@ -45,6 +45,35 @@
       <scope>test</scope>
     </dependency>
   </dependencies>
+  <profiles>
+    <!-- Activate PGP signing only when performing a release -->
+    <profile>
+      <id>release-sign-artifacts</id>
+      <activation>
+        <property>
+          <name>performRelease</name>
+          <value>true</value>
+        </property>
+      </activation>
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-gpg-plugin</artifactId>
+            <executions>
+              <execution>
+                <id>sign-artifacts</id>
+                <phase>verify</phase>
+                <goals>
+                  <goal>sign</goal>
+                </goals>
+              </execution>
+            </executions>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
+  </profiles>  
   <build>
     <defaultGoal>package</defaultGoal>
     <plugins>