Upgrade from Java 8 to Java 11 (Spring Boot 2.7.18, Gradle 7.6.4)

[devin-ai-integration]

Summary

Upgrades the project to build and run on Java 11, keeping Maven and Gradle definitions in sync:

• pom.xml: java.version 1.8 → 11, spring-boot-starter-parent 2.0.2.RELEASE → 2.7.18 (last 2.x line, officially supports Java 11). spring-boot-properties-migrator kept for now; startup logs show no property-migration warnings, so it can be removed in a follow-up. Also changed <packaging>pom</packaging> → jar — with pom packaging Maven never compiled the sources, so the Java 11 build could not actually be verified.
• build.gradle: spring-boot-gradle-plugin → 2.7.18, sourceCompatibility/targetCompatibility → JavaVersion.VERSION_11, compile/testCompile → implementation/testImplementation, bootJar { baseName/version } → archiveBaseName/archiveVersion (removed in Gradle 7). Added spring-boot-starter-jdbc, h2, and spring-boot-properties-migrator to match the Maven dependency set (Gradle build previously lacked them and Application.java's JdbcTemplate usage failed to compile).
• Gradle wrapper: 4.6 → 7.6.4 (Gradle 4.x cannot run Spring Boot 2.7 / Java 11); gradlew/mvnw made executable.
• Application.java: wrapped the startup RestTemplate calls to gturnquist-quoters.cfapps.io in try/catch — that service is long dead (UnknownHostException), and with Spring Boot 2.7 the failing CommandLineRunner aborted application startup. No other source changes were needed; no removed Java 8 APIs are used.

Verification (JDK 11.0.28)

• ./mvnw clean verify — BUILD SUCCESS (sources compiled, jar packaged)
• ./gradlew clean build — BUILD SUCCESSFUL
• App starts (java -jar target/gs-spring-boot-0.1.0.jar); GET /, GET /topic, GET /datetime all respond correctly; no properties-migrator warnings in logs.

Link to Devin session: https://app.devin.ai/sessions/ea4c7c6a661f4c73b3b83b66302fab93

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