How to encode WebP animation on Android

Question

I cannot find documentation or sample code on how to create an animation file in WebP format on Android. I know how to encode one WebP image from a bitmap. I also know that there is a webpmux command-line utility for combining multiple WebP images into a single WebP file containing multiple frames. I do not know how to do this from Java code.

I am pleased using the SDK with the high version of Android, 4.3+ is fine, which means that WebP must be fully supported.