Any good tutorials for creating Bamboo Notification plugin modules

Hello,

Anyone have any good documentation link for creating Bamboo Notification plugin modules?

I have created one by following some portions of below doc but I am getting a null pointer when it tries the get the freemarker HTML. When I looked at the logs I see that the templateRenderer is loading as NULL.

https://developer.atlassian.com/server/bamboo/building-a-notification-plugin/

Any help on this is greatly appreciated.

Thanks
Ravi

Here is a part of stacktrace

[INFO] [talledLocalContainer] 2019-03-07 16:07:31,398 INFO [http-nio-6990-exec-10] [AccessLogFilter] admin GET http://localhost:6990/bamboo/chain/admin/ajax/addNotification.action?saved=true&buildKey=SPIR-SPLAN&lastModified=0&returnUrl=%2Fchain%2Fadmin%2Fconfig%2FdefaultChainNotification.action%3FbuildKey%3DSPIR-SPLAN&bamboo.successReturnMode=json&decorator=nothing&confirm=true&_=1551992718094 164379kb
[INFO] [talledLocalContainer] 2019-03-07 16:07:31,544 ERROR [http-nio-6990-exec-10] [runtime] Error executing FreeMarker template
[INFO] [talledLocalContainer] FreeMarker template error:
[INFO] [talledLocalContainer] Java method “com.spira.plugin.SpiraNotificationRecipient.getEditHtml()” threw an exception when invoked on com.spira.plugin.SpiraNotificationRecipient object “com.spira.plugin.SpiraNotificationRecipient”; see cause exception in the Java stack trace.
[INFO] [talledLocalContainer]
[INFO] [talledLocalContainer] ----
[INFO] [talledLocalContainer] FTL stack trace ("~" means nesting-related):
[INFO] [talledLocalContainer] - Failed at: ${recipient.getEditHtml()} [in template “lib/build.ftl” in macro “commonNotificationFormContent” at line 442, column 9]
[INFO] [talledLocalContainer] ~ Reached through: #nested [in template “freemarker-lib/ui.ftl” in macro “bambooSection” at line 124, column 9]
[INFO] [talledLocalContainer] ~ Reached through: ui.bambooSection dependsOn=“notifica… [in template “lib/build.ftl” in macro “commonNotificationFormContent” at line 441, column 9]
[INFO] [talledLocalContainer] - Reached through: commonNotificationFormContent showAc… [in template “lib/build.ftl” in macro “configureBuildNotificationsForm” at line 405, column 9]
[INFO] [talledLocalContainer] ~ Reached through: #nested [in template “freemarker-lib/ui.ftl” in macro “bambooSection” at line 124, column 9]
[INFO] [talledLocalContainer] ~ Reached through: ui.bambooSection titleKey=”${titleKe… [in template “lib/build.ftl” in macro “configureBuildNotificationsForm” at line 404, column 5]
[INFO] [talledLocalContainer] - Reached through: bd.configureBuildNotificationsForm g… [in template “chain/add/addNotification.ftl” at line 9, column 5]
[INFO] [talledLocalContainer] - Reached through: ww.form action="configureChainNotifi… [in template “chain/add/addNotification.ftl” at line 4, column 1]