feature/scaffold book api and createBook service logic and tests

[codesungrape]

This Pull Request establishes the foundational architecture and implements the core business logic for the POST /books operation within the Service layer, strictly adhering to HMCTS standards. All core logic has been developed using a Test-Driven Development (TDD) approach.

Feature

• createBook(BookRequest)

HMCTS Architectural Compliance
The following HMCTS mandates were enforced in this PR:

• TDD Principle: Service methods are covered by dedicated unit tests (BookServiceTest), ensuring robust and testable business logic.
• Separation of Concerns: Clearly separated application into dto, entity, repository, and service layers.
• Immutability: BookRequest DTO utilizes Lombok @value for immutable inbound data handling.
• Naming Consistency: Uses @JsonProperty to correctly map HMCTS-mandated snake_case JSON properties to internal Java camelCase fields.
• Entity Design: Book entity uses @builder pattern for clean construction and has corrected package imports.

Review Focus

• Logic: Please verify the createBook implementation in BookService.java, particularly the DTO-to-Entity mapping via the builder.
• Testing: Review BookServiceTest.java to confirm correct usage of Mockito (when/verify) and assertion coverage for the createBook happy path and the deleteBook 404 exception path.

Next Steps (Future PRs)
This PR does not include the final API endpoints. The next steps will link this logic to the external contract:

1. Implement BookController (Linking the POST /books request to the service).
2. Implement Global Exception Handler (Ensuring all exceptions, like 404, return the HMCTS Problem JSON format).

[Copilot]

Pull Request Overview

This PR establishes the foundational service layer for a Book API, implementing the createBook operation with comprehensive test coverage using TDD principles. The implementation follows HMCTS architectural standards with clear separation of concerns across DTOs, entities, repositories, and services.

Key Changes:

• Implemented createBook service method with validation logic and DTO-to-Entity mapping
• Created comprehensive unit tests covering happy path, validation, edge cases, and error scenarios
• Established Book entity with UUID-based identification, soft-delete support, and JPA annotations
• Defined immutable BookRequest DTO with validation constraints and JSON property mapping

Reviewed Changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
BookService.java	Core service implementation with createBook method, validation logic, and entity mapping
BookServiceTest.java	Comprehensive unit tests with Mockito mocks covering success, validation, repository failures, and edge cases
Book.java	JPA entity with UUID primary key, soft-delete flag, timestamp tracking, and Lombok builder pattern
BookRequest.java	Immutable DTO with @notblank validation and @JsonProperty for snake_case mapping
BookRepository.java	Spring Data JPA repository interface with custom query methods for soft-delete support
openapi.yml	OpenAPI 3.0.3 specification defining Book API contract with UUID-based identifiers
application.yaml	Basic Spring application configuration
build.gradle	Added junit-jupiter-params dependency for parameterized testing
BookApiApplication.java	Spring Boot application entry point
BookApiApplicationTests.java	Basic Spring context load test

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[codesungrape]

@copilot open a new pull request to apply changes based on the comments in this thread

[Copilot]

@codesungrape I've opened a new pull request, #2, to work on those changes. Once the pull request is ready, I'll request review from you.