Function paymentMiddleware

paymentMiddleware(
    routes: RoutesConfig,
    server: t402ResourceServer,
    paywallConfig?: PaywallConfig,
    paywall?: PaywallProvider,
    syncFacilitatorOnStart?: boolean,
): (req: Request, res: Response, next: NextFunction) => Promise<void>
Express payment middleware for t402 protocol (direct server instance).

Use this when you want to pass a pre-configured t402ResourceServer instance. This provides more flexibility for testing, custom configuration, and reusing server instances across multiple middlewares.
Parameters
- routes: RoutesConfig
  Route configurations for protected endpoints
- server: t402ResourceServer
  Pre-configured t402ResourceServer instance
- OptionalpaywallConfig: PaywallConfig
  Optional configuration for the built-in paywall UI
- Optionalpaywall: PaywallProvider
  Optional custom paywall provider (overrides default)
- syncFacilitatorOnStart: boolean = true
  Whether to sync with the facilitator on startup (defaults to true)
Returns (req: Request, res: Response, next: NextFunction) => Promise<void>
Express middleware handler
Example
```
import { paymentMiddleware } from "@t402/express";
import { t402ResourceServer } from "@t402/core/server";
import { registerExactEvmScheme } from "@t402/evm/exact/server";

const server = new t402ResourceServer(myFacilitatorClient);
registerExactEvmScheme(server, { signer: myServerSigner });

app.use(paymentMiddleware(routes, server, paywallConfig));
```
- Defined in http/express/src/index.ts:73