Is there any Resource Type that can be used to call person extra information?

Summary:

Making a REST call in Alert Composer to retrieve Person Extra Information field

Content (required):

On demand of a client, need to make a REST call to display a field call Probation End Date (stored in person extra information) in Alert Composer. However, we are not finding a resource type that can make this call. Is this possible?

Version (include the version you are using, if applicable):

23B

Code Snippet (add any code snippets that support your topic, if applicable):