Boundary Warp is a new feature found in Adobe Camera Raw 9.4 or greater and Adobe Lightroom 6.4 or greater.
This feature will adaptively stretch or reshape the edges of a stitched panorama to fill the rectangle boundary. The user can automatically crop the images or take the results into Adobe Photoshop and use Content Aware fill, Liquify, or Adaptive Wide Angle adjustments. Special note: Boundary Warp may not work well on images with straight lines or architectural features near the edges of the image. The process of warping the image may distort your images. Be sure to watch my Boundary Warp Advanced Tips and Techniques video for additional information for correcting this issue. vimeo.com/152773100
Special note: This new feature is not found in the standalone version of Lightroom 6.4.
Feature updates between major releases are only available to Creative Cloud subscribers.