/**
 * Performs a shallow merge of two objects.
 * Optionally allows overwriting undefined properties in the target object with values from the source.
 *
 * @param target - The target object to be merged.
 * @param source - The source object for the merge.
 * @param overwriteUndefinedProperties - Flag to overwrite 'undefined' properties in the target.
 * @returns A new object that is a shallow merge of the target and source objects.
 */
export declare function shallowMerge<TTarget extends Record<string, unknown>, TSource extends Record<string, unknown>>(target: TTarget, source: TSource, overwriteUndefinedProperties?: boolean): TTarget & TSource;