code: func (configMgr *ConfigurationManager) IsKeyExist(key string) bool {
  	configMgr.configMapMux.Lock()
  	defer configMgr.configMapMux.Unlock()
  
  	if _, ok := configMgr.ConfigurationMap[key]; ok {
  		return true
  	}
  
  	return false
  }
docs: // IsKeyExist check if key exsist in cache