Function validate_repository_concurrency 

pub fn validate_repository_concurrency(
    concurrency: Option<&ConcurrencySpec>,
    context: &str,
) -> Vec<ValidationError>

spec.concurrency rules shared by Repository and ClusterRepository (context names the kind for the message). maxConcurrentDeleteJobs must be at least 1: 0 would never delete anything, and there is deliberately no “unlimited” spelling. maxConcurrentJobs keeps its own contract (0 means unlimited), so it is not checked here.