I have whitelisted this usage only because it is still used in this fairly active pods plugin, even though it was found in /plugins/pods/deprecated/deprecated.php which shows that even the developers know that this code is deprecated and should be removed. This code probably isn’t even safe any more because the file it includes has not existed in any WordPress distribution since 3.8.9 which is over 10 years old now. So if this code was executed on any WordPress site that has updated within the last ten years then it would cause a fatal error for trying to include a file that doesn’t exist. But it’s not malicious so I have decided to whitelist it for now.
I may even change my mind and re-include this code later because it is unsafe and if you were to use my plugin to fix this file and remove that include line then it would only serve to prevent your site from crashing on this error if your json_encode function were somehow blocked or removed from your PHP libraries.