Upgrade to Spring Boot 3.4.5 and Java 21

[devin-ai-integration]

Summary

Upgrades the project from Spring Boot 2.0.2 / Java 8 to Spring Boot 3.4.5 / Java 21, along with build tool and code fixes required for compatibility.

Changes

Build configuration:

• pom.xml: Spring Boot parent 2.0.2.RELEASE → 3.4.5, Java 1.8 → 21, removed spring-boot-properties-migrator dependency, fixed packaging from pom to jar
• build.gradle: Plugin version 2.0.2.RELEASE → 3.4.5, Java 1.8 → 21, compile/testCompile → implementation/testImplementation, added spring-boot-starter-jdbc and h2 dependencies
• Gradle wrapper: 4.6 → 8.12
• Maven wrapper: 3.3.9 → 3.9.9

Code fixes:

• Fixed H2 SQL syntax: DROP TABLE customers IF EXISTS → DROP TABLE IF EXISTS customers (H2 2.x compatibility)
• Removed defunct REST API calls to gturnquist-quoters.cfapps.io (URL no longer available)
• Removed unused RestTemplate bean, CommandLineRunner run bean, and related imports (Quote, RestTemplateBuilder, RestTemplate, Bean)
• JDBC CommandLineRunner via run(String... args) method retained

Documentation:

• Updated README with Java 21 / Spring Boot 3.4.5 requirements and build instructions

Review & Testing Checklist for Human

• Run ./mvnw clean package — verify compilation succeeds with Java 21
• Start app with java -jar target/gs-spring-boot-0.1.0.jar and verify endpoints: /, /topic, /datetime, /topic/string/operation, /topic/file/operation
• Verify H2 database initialization (customer table creation and queries logged on startup)

Notes

• The pom.xml packaging was changed from pom to jar — the original pom packaging prevented Maven from compiling sources. This was likely a pre-existing issue.
• All endpoints tested locally and working: /, /topic, /datetime, /topic/string/operation, /topic/file/operation

Link to Devin session: https://app.devin.ai/sessions/3bbe8ad46c3a4034a0678d19dc387d03
Requested by: @jerryoliphant-cog

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Devin Review

Status	Commit
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Testing Results

Built from source with Maven + Java 21, started the jar, verified all REST endpoints via curl. All 9 tests passed.

Test Results (9/9 passed)

Test	Result
Maven build (./mvnw clean package)	passed — BUILD SUCCESS, exit 0
App startup (H2 init, no errors)	passed — tables created, customers inserted, no ERROR logs
GET /	passed — {"id":1,"content":"Hello, World!"}
GET /topic	passed — 3 topics with correct ids and fields
POST + GET /topic/test	passed — created and retrieved topic
GET /datetime	passed — datetime, leap year, timezone all present
GET /topic/string/operation	passed — join and filter results correct
GET /topic/file/operation	passed — file listing, find, and read all work
GET /topic/sort	passed — alphabetical order (java, javascript, spring)

Startup log verification

Assertion	Result
Started Application present	1 match
Creating tables present	1 match
Inserting customer record for John Woo present	1 match
Querying for customer records present	1 match
Connection refused absent	0 matches
gturnquist-quoters absent	0 matches
ERROR absent	0 matches

Devin session