Added -link options to Javadoc plugin

pom.xml

@@ -215,7 +215,7 @@
               !${project.groupId}.example.*,
               !${project.groupId}.logging.*,
               !${project.groupId}.util.*,
-              ${project.groupId}.*
+              ${project.groupId}.*;version=${project.version}
             </Export-Package>
             <Private-Package>
               ${project.groupId}.example.*,
@@ -350,13 +350,23 @@
             -windowtitle "${project.name} ${project.version} API Reference"
             -doctitle "${project.name} ${project.version} API Reference"
             -bottom "Copyright © ${project.inceptionYear}-Present ${project.organization.name}. All Rights Reserved."
+
             -link http://java.sun.com/javase/6/docs/api/
+            -link http://code.google.com/apis/protocolbuffers/docs/reference/java/
+            -link http://www.osgi.org/javadoc/r4v41/
+            -link http://google-guice.googlecode.com/svn/trunk/javadoc/
+            -link http://static.springframework.org/spring/docs/2.5.x/api/
+            -link http://www.slf4j.org/apidocs/
+            -link http://commons.apache.org/logging/commons-logging-1.1.1/apidocs/
+            -link http://logging.apache.org/log4j/1.2/apidocs/
+
             -group "Low-level data representation" ${project.groupId}.buffer*
             -group "Central interface for all I/O operations" ${project.groupId}.channel*
             -group "Client &amp; Server bootstrapping utilities" ${project.groupId}.bootstrap*
             -group "Reusable I/O event interceptors" ${project.groupId}.handler*
             -group "IoC (Dependency Injection) container integration" ${project.groupId}.container*
             -group "Miscellaneous" ${project.groupId}.logging*
+
             -nopackagediagram
             -sourceclasspath ${project.build.outputDirectory}
           </additionalparam>