Homebrew: Cask 'java' definition is invalid

I started getting the following error when updating my casks recently:

Error: Cask 'java' definition is invalid: Token '{:v1=>"java"}' in header line does not match the file name.

I'm on MacOS 10.14.4, and my Homebrew version:

→ brew --version
Homebrew 2.1.2
Homebrew/homebrew-core (git revision 6811d1; last commit 2019-05-11)
Homebrew/homebrew-cask (git revision ba4e3; last commit 2019-05-11)

Here's the output of brew cask upgrade --verbose --debug:

Updating Homebrew...
==> Auto-updated Homebrew!
Updated 2 taps (homebrew/core and homebrew/cask).
==> Updated Formulae
angular-cli          atlassian-cli        libpqxx              terraforming
app-engine-python    elasticsearch        osm2pgrouting
asciidoctorj         jenkins-lts          postgresql

==> Casks with `auto_updates` or `version :latest` will not be upgraded
==> Upgrading 1 outdated package:
Error: Cask 'java' definition is invalid: Token '{:v1=>"java"}' in header line does not match the file name.
/usr/local/Homebrew/Library/Homebrew/cask/cask_loader.rb:73:in `cask'
/usr/local/Caskroom/java/.metadata/1.8.0_51-b16/20150725210402.758/Casks/java.rb:1:in `load'
/usr/local/Homebrew/Library/Homebrew/cask/cask_loader.rb:62:in `instance_eval'
/usr/local/Homebrew/Library/Homebrew/cask/cask_loader.rb:62:in `load'
/usr/local/Homebrew/Library/Homebrew/cask/cask_loader.rb:178:in `load'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/upgrade.rb:39:in `block in run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/upgrade.rb:37:in `each'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/upgrade.rb:37:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/abstract_command.rb:36:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:92:in `run_command'
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:158:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:123:in `run'
/usr/local/Homebrew/Library/Homebrew/cmd/cask.rb:9:in `cask'
/usr/local/Homebrew/Library/Homebrew/brew.rb:102:in `<main>'
Error: Kernel.exit
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:162:in `exit'
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:162:in `rescue in run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:146:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:123:in `run'
/usr/local/Homebrew/Library/Homebrew/cmd/cask.rb:9:in `cask'
/usr/local/Homebrew/Library/Homebrew/brew.rb:102:in `<main>'

and the output of brew tap:

beeftornado/rmtree
heroku/brew
homebrew/cask
homebrew/core
homebrew/services

Here's the output of brew doctor if it helps:

→ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: "config" scripts exist outside your system or Homebrew directories.
`./configure` scripts often look for *-config scripts to determine if
software packages are installed, and which additional flags to use when
compiling and linking.

Having additional scripts in your path can confuse software installed via
Homebrew if the config script overrides a system or Homebrew-provided
script of the same name. We found the following "config" scripts:
  /Users/myUser/anaconda3/bin/icu-config
  /Users/myUser/anaconda3/bin/krb5-config
  /Users/myUser/anaconda3/bin/freetype-config
  /Users/myUser/anaconda3/bin/xslt-config
  /Users/myUser/anaconda3/bin/libpng16-config
  /Users/myUser/anaconda3/bin/python3.6m-config
  /Users/myUser/anaconda3/bin/libpng-config
  /Users/myUser/anaconda3/bin/xml2-config
  /Users/myUser/anaconda3/bin/python3-config
  /Users/myUser/anaconda3/bin/curl-config
  /Users/myUser/anaconda3/bin/ncursesw6-config
  /Users/myUser/anaconda3/bin/pcre-config
  /Users/myUser/anaconda3/bin/python3.6-config
  /Applications/Postgres.app/Contents/Versions/9.4/bin/gdal-config

Warning: Some installed formulae are not readable:
  dotwrp: Unsupported special dependency :fortran
(base)

I've searched but cannot seem to find a way to fix this. Any suggestions?

Solution

Solved by doing the following:

Edited the java cask:

vim /usr/local/Caskroom/java/.metadata/1.8.0_51-b16/20150725210402.758/Casks/java.rb

Changed the first line from:

cask :v1 => 'java' do

cask 'java' do

Removed the undent comments at the end of the cask, which were giving me problems.
Ran brew uninstall --cask java

Problem solved 💥