How to create Contexual Content Variables(CCVAR) Custom Properties

[Lavita]

We are on AEM 6.5 and using acs commons package - 5.4.0.

We are able to OOTB features of CCVAR i.e. 

• page_properties
• inherited_page_properties

But we want to use custom properties with custom prefix(Read a configuration/component and get values from it instead of using page properties). Tried to extend the properties as per

(https://adobe-consulting-services.github.io/acs-aem-commons/features/contextual-content-variables/i...) but could not.

Has anyone tried implementing ContentVariableProvider and was able to add custom properties?