presto-main/src/main/java/io/prestosql/execution/QueryManagerConfig.java/QueryManagerConfig/setRequiredWorkers
class QueryManagerConfig:    @Config("query-manager.required-workers")
    @ConfigDescription("Minimum number of active workers that must be available before a query will start")
    public QueryManagerConfig setRequiredWorkers(int requiredWorkers)
    {
        this.requiredWorkers = requiredWorkers;
        return this;
    }