@NonNull

Runtime null-safety on fields (and method parameters where supported).

Kind	Runtime
Backends	legacy, stage3
Requires generate	No

When to use

• Enforce non-null invariants on mutable properties
• Document intent at decoration sites (similar to Java @NonNull)

When not to use

• Optional fields — leave undecorated or use ? in TypeScript
• Compile-time-only guarantees — TypeScript strict mode remains the primary tool

Example

import { NonNull } from 'lombok-typescript/legacy';

class Account {
  @NonNull
  owner!: string;
}

Assigning null or undefined throws at runtime.

Legacy vs Stage 3

• Legacy: field decorator on property declarations
• Stage 3: single-argument initializer decorator form per ECMAScript spec

v0.1 limitations

• Runtime check only; does not change TypeScript's static type to exclude null from the declared type.
• Does not generate codegen companions.