getContents not working in 8.2.0 or 8.3.0

I have an annotationChanged listener that inspects the annotations passed to it. It receives annotations created by the AnnotationTextHighlight tool, and retrieves the text selection with annotation.getContents(). This works fine in 8.1.1. In 8.2.0 and 8.3.0, getContents returns undefined.

I’m using PDF.js Express Plus via npm.