Easy possiblity to set CONCURRENT Features on Specification level

Is your feature request related to a problem?

We have tests that typically rely on SAME_THREAD Specifications, SAME_THREAD Features. (https://spockframework.org/spock/docs/2.1/parallel_execution.html Figure 1)

However we have single Specifications where all Features can ran concurrently.
Those specifications shall be still ran as SAME_THREAD, but the Features can be CONCURRENT.

Instead of annotating each single Feature in the Specification with @Execution(ExecutionMode.CONCURRENT) I'd like to have a simpler solution.

Describe the solution you'd like

An Annotation on Specification level to mark all Features as concurrent.

Or extend @ExecutionMode with values for Specification and Features.
@ExecutionMode(specification = SAME_THREAD, feature = CONCURRENT)

The specification might be ignored if set on Feature level (or throws an error).

The current value could still be honored maintaining backwards compatibility.
If set on Feature level an also set feature might be ignored (or throws an error).
If set on Specification level an also set specification might be ignored (or throws an error).

Describe alternatives you've considered

Annotating all Features in the Specification with @Execution(ExecutionMode.CONCURRENT).

That works. But is cumbersome and error-prone.

Additional context

No response

Start by tracing how @Execution and ExecutionMode are interpreted at Specification and Feature levels. Define the annotation behavior so a Specification can remain SAME_THREAD while its Features default to CONCURRENT, preserve the current value behavior, and decide how conflicting settings are handled; verify both Specification-level and Feature-level cases with the project’s test suite.