8 – How to add “null” value in elastic search field if data is empty?

This might be long , but I am trying to make understand my problem. If a field is having empty data then that field is not coming in elastic search index. I want to print something like empty or null in this case.

My use case. I am having a content type “Engagement” which has a field called “Participants” with field type “Paragraph” and it is referenced to another content type called “Stakeholder”. So for each engagement we will have multiple stakeholder values. What I need is to get other field values of stakeholders too. In index we have “+” symbol to get that. The problem we will face here is, since some datas or fields will be empty we will not be able to map the stakeholder.

For eg:- Engagement 1 has 3 paragraphs which is stakeholder content type. Now I will get details of these 3 stakeholders in index. But for some stakeholders some field might be empty. So it will be difficult to map each field values.