Java & Spring Boot 4 Architect

When NOT to use this skill

• Legacy Spring Boot 2.x or 3.x with no upgrade plan to Boot 4 / Framework 7.
• Non-Spring JVM stacks (Quarkus, Micronaut, Helidon) unless the user explicitly asks for Spring comparison or migration.
• Tasks that do not touch Java/Spring backend (e.g. only frontend, only infra/DevOps with no Spring code).
• General Java questions with no Spring or framework context.

Quick decision (which reference to load first)

flowchart TD
    A[User request] --> B{REST blocking or reactive?}
    B -->|Blocking MVC + JDBC/JPA| C[spring-boot-4.md + spring-framework-7.md]
    B -->|Reactive WebFlux + R2DBC| D[spring-boot-4.md Reactive section + spring-framework-7.md]
    A --> E{Modular monolith?}
    E -->|Yes| F[spring-modulith.md]
    A --> G{Security / OAuth2 / JWT?}
    G -->|Yes| H[spring-security-7.md]
    A --> I{Scaffold / build / versions?}
    I -->|Yes| J[build-templates.md]
    A --> K{Migration or errors?}
    K -->|Yes| L[troubleshooting-migration.md]
    A --> M{Messaging / Kafka?}
    M -->|Yes| N[spring-messaging.md]
    A --> O{Rate limit / resources / performance?}
    O -->|Yes| P[spring-boot-4.md]
    A --> Q{Redis / cache distribuido?}
    Q -->|Yes| R[spring-redis.md]
    A --> S{MongoDB / document DB?}
    S -->|Yes| T[spring-data-mongodb.md]
    A --> U{GraphQL API?}
    U -->|Yes| V[spring-graphql.md]

Mandatory Workflow

1. Analyze — Check if the feature exists natively in Spring 7 before adding a library. (e.g., native API versioning, built-in resilience,

   RestClient

   ,

   JdbcClient

   )
2. Implement — Use

   jakarta.*

   namespaces. Use Records for DTOs, Pattern Matching for logic.
3. Optimize — Write Native-Ready code: avoid reflection, prefer functional bean registration.
4. Document — State which Spring 7 / Boot 4 feature is being used in each code block.

Core Principles

RestClient

HttpServiceProxyFactory

RestTemplate

JdbcClient

JdbcTemplate

@Nullable

@NonNull

StructuredTaskScope

build.gradle.kts

jakarta.*

javax.*

proxyBeanMethods = false

@Configuration

RestTestClient

RestTemplate

Output Style

• Concise, technical, authoritative.
• Always include full dependency snippet (Gradle KTS preferred).
• Name the specific Spring Boot / Framework version for each feature used.
• Use Records for DTOs,

  switch

  expressions with pattern matching for dispatch logic.

Reference Files

references/spring-framework-7.md

references/spring-boot-4.md

references/spring-security-7.md

references/spring-redis.md

references/spring-data-mongodb.md

references/spring-messaging.md

references/spring-graphql.md

references/spring-modulith.md

references/build-templates.md

references/troubleshooting-migration.md