With the release of 4.0.0 the default device model was updated from Galaxy Nexus (AOSP 4.x.x) to a Nexus 5X (AOSP 6.x) device. As a result some fields have changed values, some fields were deprecated (now returning null). These are upstream changes from Google not from the library itself. The benefit of the update, however, far outweighs these changes by allowing for more applications to be downloaded by the library.

Some of these changes are reflected in changes to the CLI tool /~https://github.com/dweinstein/node-google-play-cli/commit/efe9047bd68d0d345d69156a347e7da057e3caec. But if you don't use the CLI tool then you will need to adjust your code.

details.appDetails.certificateHash - now returning an empty array as it is replaced by certificateSet

details.appDetails.certificateSet returns an array of objects with certificateHash field set.

details.appDetails.numDownloads field now returns something like "100,000+ downloads" -- this is an upstream change from google.

There might be other changes that were missed, caveat emptor.