Custom methods is not possible in bamboo plugin, Not able to call it from freemarker template

[dnyaneshwar_nagre]

I created freemarker file i.e editConfigTask.ftl and  tried to call a custom method in ConfigTask class but not able to call a custom method on the submit button or search button, Because Bamboo provides AbstractTaskConfigurator Abstract class and it's having populateContextForCreate, populateContextForEdit, validate and generateTaskConfigMap methods, So its not provides the way to call custom methods.

Can you please guide me, How to call custom methods from freemarker template on search button?