• Java 17: Functional programming features, records, sealed classes, performance considerations.
• GCP: Familiarity with Cloud Run or GKE, Cloud SQL, Cloud Storage, Secret Manager, IAM, VPC; cost/perf trade-offs.
• Spring Boot: Auto-configuration, profiles, Spring Data/JPA, WebFlux (nice), validation, actuator.
• Apache Kafka: Topic design, partitioning strategy, consumer groups, offsets, retries/DLQ, schema registry/Avro/Protobuf.
• Software Engineering Fundamentals: DDD concepts, SOLID, testing (unit/integration), performance profiling, and security basics (OAuth2/JWT, OWASP Top 10).

Non-Mandatory (Nice-to-Have)

• Messaging systems: RabbitMQ, GCP Pub/Sub, or SQS/SNS.
• Observability: Prometheus/Grafana, ELK/EFK, OpenTelemetry, distributed tracing.
• Build & Infra: Maven/Gradle tuning, Helm charts, Terraform, Argo CD.
• Security: mTLS, secrets rotation, vulnerability scanning (Snyk/Trivy), supply chain...