Getting the confluence Page FULL high-lighted text

Hi,
I need to fetch “highlighted” text on which inline comment has been posted. Same as in this issue:

I’ve got problem with text being “croped” - if text is to long (more than 256 characters) it will be cut. Unfortunately, there is no answer in foregoing post.

At present I do GET request that looks like this:
http://my-project.com/confluence/rest/api/content/${my_page_id}?expand=extensions.inlineProperties

and returns:

{

   extesnions : {
       inlineProperties: {
           originalSelection : "First 252 chars of my comment...",
           markerRef:"<someMarkerRef>"
      },
      ...
  }
  ...
}

How can I fetch full marked text? I can’t find “Get by marker-ref” api-request.