merge(other) {
		const newSpecifiersMap = new Map(this.specifiers);
		for (const [name, specifiers] of other.specifiers) {
			if (newSpecifiersMap.has(name)) {
				const currentSpecifiers =
					/** @type {Set<string>} */
					(newSpecifiersMap.get(name));
				for (const spec of specifiers) currentSpecifiers.add(spec);
			} else {
				newSpecifiersMap.set(name, specifiers);
			}
		}
		return new ExternalModuleInitFragment(
			this.importedModule,
			newSpecifiersMap,
			this.defaultImport
		);
	}
@param {ExternalModuleInitFragment} other other
@returns {ExternalModuleInitFragment} ExternalModuleInitFragment