Develop an online food delivery system. There are multiple restaurants $($producers$)$ preparing food orders and delivery drivers $($consumers$)$ picking up and delivering orders to customers. To solve the producer$-$consumer problem in this scenario, you can use Java Threads and synchronization.

Problem: How can you ensure that restaurant threads $($producers$)$ safely add orders to a shared buffer, and delivery driver threads $($consumers$)$ retrieve and deliver orders without conflicts?