What does a `data class` give you (and when is it a good fit)?

Deep dive

A `data class` is a convenient way to declare value-like types. Kotlin generates:

• `equals()` / `hashCode()` based on constructor properties
• `toString()`
• `copy(...)`
• `componentN()` for destructuring

When it’s a good fit

• DTOs, request/response models, configuration objects.
• Domain value objects where equality is “by data”.

Practical notes

• `copy()` is shallow (it copies references).
• Prefer `val` properties for immutability; `data class` itself doesn’t enforce it.

Common pitfalls

• Using mutable properties in keys for HashMap/HashSet.
• Expecting inheritance behavior (data classes are final by default).
• Treating `copy()` as deep clone.