Skill: java-immutability-modeling

Activation Contract

Use this skill when modeling Java data with records, value objects, immutable classes, defensive copies, collection ownership, equality, and state validation.

Do not use this skill for persistence mapping only, serialization-only configuration, generic DTO naming, or non-Java data modeling.

Responsibility

This skill teaches safe Java state modeling. It does not call other skills, impose immutability everywhere, or choose framework annotations unless context requires them.

Required Context

• Java version.
• Whether the type is domain model, value object, DTO, event, command, or persistence entity.
• Mutability requirements and ownership of collections.
• Equality/hashCode expectations.