protected function _getExistsConfig() {
		$defaultConfigsDBconn = $this->_getDefaultConfigs();
		$customConfigsDBconn = $this->ConfigInstaller->getCustomConnectionsConfig();
		$configsDBconn = $defaultConfigsDBconn + $customConfigsDBconn + ['test' => $defaultConfigsDBconn['default']];
		$currConfigDBconn = $this->ConfigInstaller->getListDbConnConfigs();
		$existConfigDBconn = array_intersect_key($configsDBconn, array_flip($currConfigDBconn));
		if (empty($existConfigDBconn)) {
			$existConfigDBconn = array_intersect_key($configsDBconn, ['default' => null]);
		}

		return $existConfigDBconn;
	}