Journal entry for Contract Labor

I mean, you're certainly capable of doing so.

Whether it would be a good idea is down to the details of your situation. What real-world situation are you trying to mirror with the GJE?

@RealDealCG 

I can't imagine a scenario where you would debit (reduce) sales and credit (reduce) contract labor expense.  An adjusting journal entry contains an income or expense account and a balance sheet account.