How to get the files changed in a pull request information programatically?

I am trying to get the file names of files which are changed in a pull request. I checked we can get this info using API but would like to know how we can get this information using existing atlassian bitbucket java interfaces.
Thank you.

I was using com.atlassian.bitbucket.commit.CommitService for such purposes. Extract fromRef and toRef from pull request model and based on this traverse through commits fetched by CommitService.