Adding CheckBoxMultipleChoice as a Field to customised taxonomy plugin

I am Looking to add CheckBoxMultipleChoice as field using AdditionalFieldCustomTaxonomyEditorPlugin,
it went well until populating it, I am also able to check the checkboxes, but then when I click save button on the editor it does not save it gives me java.lang.IllegalStateException: Attempt to set model object on null model of component: container-holder:container.
Please can you help me in using the CheckBoxMultipleChoice with a model on the class AdditionalFieldCustomTaxonomyEditorPlugin.

Many Thanks
Srinivas Jasti