Importing operator from plugin in multiple modules doesn't work

[bentsherman]

When importing an operator from a plugin, if you import anything from the same plugin in a different module, it fails with the following error:

https://github.com/nextflow-io/nextflow/blob/f1cffd1b28b443aa3fbd9f99404fea84613d85df/modules/nextflow/src/main/groovy/nextflow/plugin/extension/PluginExtensionProvider.groovy#L137-L139

It seems to import the operator twice and reports duplicate operators. It only seems to happen with operators, not factories or functions.

Here is a minimal test case: https://github.com/human9/nextflow-import-issue

Source: https://github.com/nextflow-io/nf-schema/pull/3