[Spring Data MongoDB 5.0] Detect missing explicit value representation configuration

Parent tracking issue

• #1081

Prerequisite

• #1082 provides the Spring Data MongoDB 5 migration composite.

Problem

Spring Data MongoDB 5 no longer provides default representations for persisted UUID, BigInteger, and BigDecimal values. Applications persisting these types must explicitly configure the corresponding representation rather than relying on earlier defaults.

Spring Data MongoDB 4 did have effective defaults for previously unconfigured applications:

• UUID: JAVA_LEGACY
• BigDecimal / BigInteger: STRING

The migration must preserve that existing behavior by making those defaults explicit. Existing explicit configuration must not be silently replaced; malformed, null, unsupported, or explicitly UNSPECIFIED values remain diagnostic because the intended representation cannot be inferred safely from source alone.

Implemented solution

PR #1098 adds FindMissingMongoValueRepresentation, a project-scoped diagnostic recipe, and AddMongoValueRepresentationProperty, a mutation recipe, that:

• Detect explicitly MongoDB-mapped UUID, BigDecimal, and non-ID BigInteger fields requiring an explicit representation, including nested collection and map-value types.
• Exclude irrelevant fields such as non-Mongo domain fields, transient/static fields, explicitly targeted numeric fields, map keys, and BigInteger IDs.
• Report all affected fields through the MongoValueRepresentationFields data table.
• Recognise valid Java configuration and Spring Boot configuration in .properties and YAML, including relaxed spellings, property placeholders, and the legacy spring.data.mongodb.uuid-representation key.
• When configuration is missing, add the Spring Data MongoDB 4 effective default: java-legacy for UUID values and string for BigDecimal/BigInteger values.
• Add those defaults to the preferred base application*.properties/.yml/.yaml file, or generate src/main/resources/application.properties when no suitable base configuration file exists.
• Flag blank, malformed, unsupported, null, or explicitly UNSPECIFIED Java, properties, and YAML configuration in place without overwriting it.
• Ignore test-source configuration when evaluating main-source persistence and continue to diagnose invalid profile overrides even when another configuration file contains a valid default.
• Avoid duplicate properties, comments, and data-table rows across recipe cycles and separate invocations.
• Compose both recipes into UpgradeSpringDataMongoDb_5_0.

Out of scope

• Inferring a representation different from the Spring Data MongoDB 4 default from existing stored BSON data.
• Rewriting existing MongoDB data.
• MongoDB dependency alignment; see #1082.
• Listener-container behaviour or removed JMX support.
• General Spring Boot property migration already handled by generated Boot property recipes.

Acceptance criteria

• UUID persistence usage is detected when no explicit UUID representation is configured.
• BigInteger / BigDecimal persistence usage is detected when no explicit numeric representation is configured.
• Existing supported Java, properties, and YAML configuration suppresses the corresponding diagnostic/default insertion.
• Missing UUID configuration receives the Spring Data MongoDB 4 default java-legacy.
• Missing BigDecimal/BigInteger configuration receives the Spring Data MongoDB 4 default string.
• A baseline configuration file is generated when required.
• Invalid, blank, malformed, null, and explicit UNSPECIFIED configuration is diagnosed in place and not silently overwritten.
• Tests cover configured, unconfigured, profile-specific, nested-value, generated-file, invalid-configuration, cross-project, composite, and idempotent cases.
• The recipes are composed into the Spring Data MongoDB 5 migration composite.

References

• Spring Data MongoDB 4.x to 5.x migration guide: https://docs.spring.io/spring-data/mongodb/reference/migration-guide/migration-guide-4.x-to-5.x.html
• Spring Boot 4.0 migration guide: https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-4.0-Migration-Guide

Review PR #1098 and the named entry points FindMissingMongoValueRepresentation, AddMongoValueRepresentationProperty, and UpgradeSpringDataMongoDb_5_0. Compare their behavior with the acceptance criteria, especially configuration detection, generated files, invalid values, nested types, cross-project handling, and idempotence; done means the listed tests and migration composition are complete.