Dependency management

[PhMemmel]

• Thirdparty libraries have to be declared according to https://moodledev.io/general/community/plugincontribution/thirdpartylibraries
• See especially point 2 in the instructions list: "Check the library is not already shipped by core - we don't want multiple versions of the same library". Guzzle, for example, is being included in moodle since 4.2. The plugin declares minimum requirements as Moodle 4.2, so probably guzzle should be removed as dependency. Please double check all other dependencies.
• The linked dev page also contains steps how to properly add a thirdparty library to the plugin (repository). A moodle admin installing a plugin expects the plugin to ship with all necessary dependencies, so the repository should include all necessary dependencies and just them (no additional development-specific ones like installed by composer). For an admin there should nothing more to be done than running git clone to install the plugin.
• Loading of dependencies must not interfere with other moodle plugins. For example, currently it is not possible to run the unit tests of other plugins (example: https://github.com/catalyst/moodle-local_aws) because of already loaded libraries. When trying to run vendor/bin/phpunit --filter=aws with repository_ocis as well as local_aws installed, it fails with error:

  
  PHP Fatal error:  Cannot redeclare GuzzleHttp\describe_type() (previously declared in /var/www/html/repository/ocis/vendor/guzzlehttp/guzzle/src/functions.php:16) in /var/www/html/local/aws/sdk/GuzzleHttp/functions.php on line 52

Fatal error: Cannot redeclare GuzzleHttp\describe_type() (previously declared in /var/www/html/repository/ocis/vendor/guzzlehttp/guzzle/src/functions.php:16) in /var/www/html/local/aws/sdk/GuzzleHttp/functions.php on line 52

The last point maybe resolves as soon as it is taken care of the fact that no libraries are being used which already exist in moodle.