Can we add custom properties in filter in AEM forms 6.5 (On prem)

 Hi,

We have a requirement to add custom properties in the filter, so that users can easily search based on the values for those properties. We have three custom property which are of type String, and I want to add them to this filter: 

I could see that OOTB, these are the only options under: /libs/cq/gui/components/coral/common/admin/customsearch/searchpredicates

Can someone suggest if we can add custom properties to filter with String values. Thank you.