# PropertyMergeStrategy

Strategy for handling nested properties in L1 property mixins.

- Source: [`core/lib/mixins/property-merge-strategy.ts`](https://github.com/aws/aws-cdk/blob/v2.274.0/packages/aws-cdk-lib/core/lib/mixins/property-merge-strategy.ts#L136)
- Type last changed: v2.254.0 · 13 May 2026

## Methods

- `combine(options?: CombineStrategyOptions): IMergeStrategy` (static) — Deep merges nested objects from source into target.

  When both the existing and new value for a key are plain objects,
  their properties are merged recursively. Primitives, arrays, and
  mismatched types are overridden by the source value.

  Supports Box-backed values: when the target value is a Box, the merge
  is deferred until the Box resolves.

- `override(): IMergeStrategy` (static) — Replaces existing property values on the target with the values from the source.

  Each allowed key is copied from source to target as-is, without
  inspecting nested objects. Any previous value on the target is discarded.