code: func (configMgr *ConfigurationManager) GetConfigurationsByKey(key string) interface{} {
  	configMgr.configMapMux.Lock()
  	sourceName, ok := configMgr.ConfigurationMap[key]
  	configMgr.configMapMux.Unlock()
  	if !ok {
  		return nil
  	}
  
  	return configMgr.configValueBySource(key, sourceName)
  }
docs: // GetConfigurationsByKey returns the value for a particluar key from cache