public static CountDownLatch awaitNextClientCallCloses(final int count) {
        final CountDownLatch newCounter = new CountDownLatch(count);
        clientCounter = newCounter;
        return newCounter;
    }
Returns a {@link CountDownLatch} that will be used in the next client calls and can be used to await the
{@link io.grpc.ClientCall.Listener#onClose(Status, Metadata) ClientCall close}. This method must be called before
the call is started.

@param count The number of call closes to await.
@return The counter used to await the client call close.
tests/src/test/java/net/devh/boot/grpc/test/config/AwaitableServerClientCallConfiguration.java