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.

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