Add Jabref 4.0 Beta. (#3921)

* Add Jabref 4.0 Beta.

* Update jabref-beta.rb

Casks/jabref-beta.rb

@@ -0,0 +1,27 @@
+cask 'jabref-beta' do
+  version '4.0-beta'
+  sha256 '0d8c6ff5979027a3c8c5da23b2ff77ae2dc62cdb0baf695e61d5da35fac0e551'
+
+  # github.com/JabRef/jabref was verified as official when first introduced to the cask
+  url 'https://github.com/JabRef/jabref/releases/download/v4.0-beta/JabRef_macos_4_0_0-beta.dmg'
+  appcast 'https://github.com/JabRef/jabref/releases.atom',
+          checkpoint: '7714d6c5bea930a04dc3caa1c6434b47e40dbae33ec472dca9bae0b10731157d'
+  name 'JabRef Beta'
+  homepage 'https://www.jabref.org/'
+
+  conflicts_with cask: 'jabref'
+
+  installer script: {
+                      executable: 'JabRef Installer.app/Contents/MacOS/JavaApplicationStub',
+                      args:       [
+                                    '-q',
+                                    '-VcreateDesktopLinkAction$Boolean=false',
+                                    '-VaddToDockAction$Boolean=false',
+                                    '-VshowFileAction$Boolean=false',
+                                    '-Vsys.installationDir=/Applications',
+                                    '-VexecutionLauncherAction$Boolean=false',
+                                  ],
+                    }
+
+  uninstall delete: '/Applications/JabRef.app'
+end