Upgrade Spring Boot and dependency versions for Java 17 compatibility

[devin-ai-integration]

Summary

Upgrades Spring Boot from 2.6.3 → 2.7.18 and all major dependencies to Java 17-compatible versions, staying on Spring Boot 2.7.x to avoid the javax→jakarta migration required by 3.x.

Dependency upgrades:

Dependency	Old	New
Spring Boot	2.6.3	2.7.18
spring dependency-management	1.0.11.RELEASE	1.1.4
DGS codegen plugin	5.0.6	5.6.7
DGS framework	4.9.21	5.5.1
MyBatis starter (+test)	2.2.2	2.3.2
jjwt (api/impl/jackson)	0.11.2	0.11.5
sqlite-jdbc	3.36.0.3	3.42.0.0
rest-assured (all 4)	4.5.1	5.3.2
spotless	6.2.1	6.22.0
joda-time	2.10.13	2.12.5

Code changes required by DGS upgrade:

• ArticleDatafetcher.java and CommentDatafetcher.java: Migrated from graphql.relay.DefaultPageInfo / graphql.relay.PageInfo to DGS-codegen-generated io.spring.graphql.types.PageInfo, using its builder API (startCursor, endCursor, hasPreviousPage, hasNextPage).

Infrastructure:

• Added settings.gradle with pluginManagement block to resolve DGS codegen plugin dependencies from Maven Central (required because the codegen core artifact is not hosted on the Gradle Plugin Portal).

Build status: Compilation and spotless checks pass. Tests have 37 failures due to NoSuchMethodError in Federation.java:194 (DGS framework runtime incompatibility), which is expected per task spec.

Review & Testing Checklist for Human

• DGS codegen plugin version: Task specified 5.6.8 but that version's core artifact is missing from Maven Central (jumps 5.6.7 → 5.6.9). This PR uses 5.6.7 — verify this is acceptable or if 5.6.9 is preferred.
• PageInfo builder field mapping: Verify the generated io.spring.graphql.types.PageInfo type has hasPreviousPage/hasNextPage fields (not hasPrevious/hasNext). Incorrect mapping would compile but produce wrong GraphQL responses.
• Test failures (37/68): All failures are NoSuchMethodError at Federation.java:194, indicating a DGS 5.5.1 runtime incompatibility. Confirm this is expected to be addressed separately, or whether a different DGS framework version (e.g., 5.5.0 or 4.x latest) would avoid this.
• settings.gradle addition: This file did not previously exist. Verify rootProject.name = 'spring-boot-realworld-example-app' matches expectations and that the pluginManagement block doesn't interfere with other build configurations.

Recommended test plan: Run ./gradlew compileJava compileTestJava spotlessCheck to confirm compilation. Run ./gradlew test and verify failures are limited to the known DGS Federation issue. Boot the app with ./gradlew bootRun and confirm it starts without errors.

Notes

• sourceCompatibility/targetCompatibility and the Gradle wrapper version are intentionally not changed — handled by separate sessions.
• The DefaultJwtServiceTest.java change is a spotless auto-format (line wrapping), no logic change.

Link to Devin session: https://app.devin.ai/sessions/17f55f06fe54418082f66fc31b983f8d
Requested by: @shayanshafii

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✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

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