Obfuscation map

Obfuscation maps are Proguard mappings from old (original) names to new (obfuscated) names for classes and class members that have been renamed. They have been exported in the client.json for every snapshot since 19w36a, and the client.json for 1.14.4 has been updated slightly after 19w36a's release to include obfuscation maps as well.

Usage
The obfuscation maps are, by design, to remap obfuscated stack traces (as in crash reports) to readable stack traces.

Dinnerbone and Adrian Östergård have suggested that the obfuscation maps may make modding easier. Searge has implied that the obfuscation maps can replace certain third-party programs such as the Mod Coder Pack.

Third party usages
The obfuscation maps include enough information to deobfuscate Minecraft for decompilation. Third-party programs may exist for this purpose.

According to the License, such decompiled source code is restricted to internal and reference use.

License
Every obfuscation map file starts with a line indicating the license of the maps. ""

In the released client obfuscation map for 19w36a,  appears as the first method entry, causing backlash from the community. Searge has clarified that this is not a deliberate arrangement.

Modder
Some Minecraft deobfuscation projects did not terminate themselves for concerns of license violations when using obfuscation maps for modding.