Addition:
Allow modules to use when: block by moving it to configuration.

when:
task.ext.when == null || task.ext.when

Allows modules to flexibly use the when: from the configuration file.
Allows conditional process execution on settings not available in the workflow block.

Configuration is set using process.ext.when allowing one to use process selectors and other configuration benefits to
apply a when condition to a group of processes or test process specific values.

Execution conditions

process {
    withName: 'FOO' {
        ext.args = 'module1,module2'
        // Example settings
        ext.when = null                           // Process executes - no conditional defined. 
        ext.when = true                          // Process executes - e.g. override for existing configuration
        ext.when = !params.skip_module // Process executes if set, or if null 
        ext.when = ext.args.tokenize(',').contains('module1')  // Process does not execute - evaluated in configuration context.
        ext.when = { task.ext.args.tokenize(',').contains('module1') }  // Process does not execute - evaluated in task context.
    }
}

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated