Using PHP 7.4 breaks composer

[morrislaptop]

I switched to PHP 7.4 to work on an old project and discovered my composer was broken, it looks from the pact-foundation/composer-downloads-plugin

I'm not sure of a way around, but thought you should know! It's been working great otherwise :)

In ExtraDownloadsPlugin.php line 25:
                                                                                   
  [ParseError]                                                                     
  syntax error, unexpected 'private' (T_PRIVATE), expecting variable (T_VARIABLE)  
                                                                                   

Exception trace:
  at /Users/craigmorris/.composer/vendor/pact-foundation/composer-downloads-plugin/src/Composer/Plugin/ExtraDownloadsPlugin.php:25
 Composer\Autoload\{closure}() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/vendor/composer/ClassLoader.php:427
 Composer\Autoload\ClassLoader->loadClass() at n/a:n/a
 spl_autoload_call() at n/a:n/a
 class_exists() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Plugin/PluginManager.php:293
 Composer\Plugin\PluginManager->registerPackage() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Plugin/PluginManager.php:492
 Composer\Plugin\PluginManager->loadRepository() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Plugin/PluginManager.php:107
 Composer\Plugin\PluginManager->loadInstalledPlugins() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Factory.php:443
 Composer\Factory->createComposer() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Factory.php:629
 Composer\Factory::create() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Console/Application.php:550
 Composer\Console\Application->getComposer() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Command/BaseCommand.php:127
 Composer\Command\BaseCommand->tryComposer() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Command/BaseCommand.php:240
 Composer\Command\BaseCommand->initialize() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/vendor/symfony/console/Command/Command.php:264
 Symfony\Component\Console\Command\Command->run() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/vendor/symfony/console/Application.php:1040
 Symfony\Component\Console\Application->doRunCommand() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/vendor/symfony/console/Application.php:301
 Symfony\Component\Console\Application->doRun() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Console/Application.php:394
 Composer\Console\Application->doRun() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/vendor/symfony/console/Application.php:171
 Symfony\Component\Console\Application->run() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/src/Composer/Console/Application.php:148
 Composer\Console\Application->run() at phar:///Users/craigmorris/Library/Application Support/Herd/bin/composer/bin/composer:93
 require() at /Users/craigmorris/Library/Application Support/Herd/bin/composer:29

update [--with WITH] [--prefer-source] [--prefer-dist] [--prefer-install PREFER-INSTALL] [--dry-run] [--dev] [--no-dev] [--lock] [--no-install] [--no-audit] [--audit-format AUDIT-FORMAT] [--no-autoloader] [--no-suggest] [--no-progress] [-w|--with-dependencies] [-W|--with-all-dependencies] [-v|vv|vvv|--verbose] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--apcu-autoloader-prefix APCU-AUTOLOADER-PREFIX] [--ignore-platform-req IGNORE-PLATFORM-REQ] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [-m|--minimal-changes] [-i|--interactive] [--root-reqs] [--] [<packages>...]