No warning on ContentPack installation if referenced Objects (e.g. DataAdapter) does not exist

[janheise]

If you install a ContentPack that contains a Search or Event Definition with a parameter, you also reference a DataAdapter.
This DataAdapter might not exist. There is no error shown during installation. Errors are only starting to show up in the log files once you start using the installed resource.

It is possible that more occurrences like this exist.

The installation process should probably warn on installation if links on resources are not valid. As a second approach, the exception that states that a resource is missing could be a notification?

e.g. see https://github.com/Graylog2/graylog-plugin-enterprise/issues/9274

• Graylog Version: 6.x