What is the Choice Router and how is it configured?

The Choice Router is Mule's conditional branching construct (equivalent to if-else). Configuration:

1. When conditions: One or more branches with a DataWeave expression. The first When branch whose expression evaluates to true is executed; others are skipped.
2. Default route: Executed when no When condition is true (equivalent to else). If no Default and no condition matches, an error is thrown. Only one route executes per message. Use cases: routing based on HTTP method, content type, field value, or customer tier. DataWeave expression example: #[payload.orderType == 'RUSH']. After the router, execution continues in the main flow. Variables/payload set inside a When branch are available after the router. Commonly used to split processing for different message types from a single endpoint.