feat: COBOL-to-Java Spring Boot migration (5 phases)

[devin-ai-integration]

Summary

Adds a complete Java Spring Boot migration of the COBOL-Examples codebase under a new java-migration/ directory. No existing COBOL files are modified. The migration covers 18 COBOL modules across 5 phases:

• Phase 1: Spring Boot 3.2.4 project with Gradle, Java 17, standard package structure
• Phase 2: JPA Account entity + AccountRepository replacing 3 COBOL SQL cursors, with Flyway-style migration SQL
• Phase 3: AccountService, StringUtils, NumericUtils, FileMergeService, SubProgramService — business logic, string/numeric ops, file SORT/MERGE, and CALL BY CONTENT/REFERENCE patterns
• Phase 4: RecordDto/RecordXmlDto DTOs with Jackson/JAXB annotations, JsonService, XmlService, ReportService for JSON GENERATE, XML GENERATE, and Report Writer replacements
• Phase 5: AccountCli (Scanner menu), CommandLineArgsRunner, AccountController (REST API)

78 test methods pass across 10 test classes (unit + integration) using H2 in PostgreSQL compatibility mode. Documentation includes README.md (module mapping table, API docs) and MIGRATION_NOTES.md (type translations, cursor mappings, design decisions).

Updates since last revision

• Added application-h2.properties profile and data-h2.sql seed data for running the app locally without PostgreSQL
• Added H2 as runtimeOnly dependency (previously test-only) to support the h2 profile
• End-to-end testing verified all REST endpoints against the running app with H2:
  • GET /accounts → 11 seed accounts returned correctly
  • GET /accounts/disabled → 3 disabled accounts (Bob, Paula, Bill)
  • GET /accounts/search?q=Tester1 → 2 matches (Mike/Tester1, Richard/Tester10)
  • Full CRUD lifecycle: POST (201) → GET (200) → PUT (200) → Toggle (Y→N) → DELETE (204) → GET (404)

Review & Testing Checklist for Human

• Fixed-width record parsing offsets in CustomerRecord.fromFixedWidth() and StudentRecord.fromFixedWidth() — verify substring positions match the actual COBOL FD record layouts in merge_sort/merge_sort_test.cbl and report_writer/report_test.cbl. These were not validated against real fixed-width input files.
• DB migration SQL (V1__create_accounts_table.sql) — verify the schema and 11 seed rows match the original sql/create_test_db.sql. Column types, nullable constraints, and default values should be compared side-by-side. Note that data-h2.sql duplicates the INSERT statements and could drift.
• AccountRepository.searchAccounts @Query — only tested against H2, not real PostgreSQL. The LIKE query across 4 columns should be validated against the actual cobol_db_example database.
• Hardcoded spring.datasource.password=password in application.properties — acceptable for a demo project but worth flagging.

Recommended test plan: Clone the branch, then:

1. cd java-migration && ./gradlew test — confirm all 78 test methods pass
2. ./gradlew bootRun --args='--spring.profiles.active=h2' — start with H2 (no PostgreSQL needed)
3. curl http://localhost:8080/accounts — verify 11 JSON accounts returned
4. Optionally test against real PostgreSQL: set up cobol_db_example database, then ./gradlew bootRun (default profile)

Notes

• AccountCli uses @Profile("cli") — confirmed it does NOT block the REST server in default mode
• All Java classes include Javadoc referencing the original COBOL source file they replace
• BigDecimal used throughout for numeric precision (mirrors COBOL packed decimal behavior)
• SubProgramService.MutableString inner class models COBOL CALL BY REFERENCE — non-standard Java pattern, but faithful to COBOL semantics
• JAXB @XmlAttribute for the enabled field and null-suppression for blank fields replicate COBOL TYPE IS ATTRIBUTE and SUPPRESS WHEN SPACES

View original video (rec-984cf386c2d94bd78ad06a29ef32b86e-edited.mp4)

Link to Devin session: https://app.devin.ai/sessions/6c03a93e63e24ca0a8feb138f0e525b9
Requested by: @jerryoliphant-cog

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