Add the kafka-basics module

kafka-basics/src/main/java/com/ankurm/kafkabasics/OrderEvent.java

@@ -0,0 +1,22 @@
+package com.ankurm.kafkabasics;
+
+import java.math.BigDecimal;
+import java.time.Instant;
+
+/**
+ * The payload. A record works as a Kafka value with no annotations at all, because Jackson 3
+ * handles records natively — but note that it needs a canonical constructor the
+ * deserializer can call, which is the one thing a record gives you for free and a Lombok
+ * {@code @Builder}-only class does not.
+ *
+ * @param orderId the partition key. Same customer, same order, same partition, same order of
+ * delivery — see docs/04-keys-and-partitions.md
+ */
+public record OrderEvent(String orderId, String customerId, BigDecimal amount, Instant placedAt) {
+
+	public static OrderEvent of(String orderId, String customerId, String amount) {
+		return new OrderEvent(orderId, customerId, new BigDecimal(amount),
+				Instant.parse("2026-08-29T10:15:30Z"));
+	}
+
+}