protected function mapParty(array $source) {
		if (!isset($source['__type'])) {
			throw new Exception('Cannot map party without explicit type (server should return "__type" in party account data):' . json_encode($source), 1354111717);
		}
		$partyType = $source['__type'];
		unset($source['__type']);
		if (isset($this->typeMapping[$partyType])) {
			$partyType = $this->typeMapping[$partyType];
		}
		$configuration = new TrustedPropertyMappingConfiguration();

		// TODO Deal with mapping errors from property mapper

		return $this->propertyMapper->convert($source, $partyType, $configuration);
	}