The obfuscation mappings released has

# (c) 2019 Microsoft Corporation. All rights reserved. ...

for the first line (license statement). Yet for all versions released in 2020 up to 20w06a (including releases and combat tests) with obfuscation mappings, the statement still declares 2019 as the copyright year. 

The year needs to be updated.

Step of checking for the latest version:

1. Go to https://piston-meta.mojang.com/mc/game/version_manifest_v2.json to find the latest list of versions. It is already sorted, with latest at top.
2. Follow the URL given by the "url" field in the latest version, such as https://piston-meta.mojang.com/v1/packages/177e49d3233cb6eac42f0495c0a48e719870c2ae/1.21.json for 1.21.
3. Search for the string "client_mappings" or "server_mappings", find the item, and follow the URL given by the "url" field, such as https://piston-data.mojang.com/v1/objects/0530a206839eb1e9b35ec86acbbe394b07a2d9fb/client.txt
4. Notice at the top of the txt file, the copyright year is still 2020, despite the version being released in 2024

Example: 20w06a client mapping file at https://launcher.mojang.com/v1/objects/63730ce216258836ad23e794ee3487b45d83ca52/client.txt