code: public function getGroupData(string $namespace) {
  		if (isset($this->groupDatas[$namespace])) {
  			return $this->groupDatas[$namespace];
  		}
  		
  		$this->groupDatas[$namespace] = $this->readCachedGroupData($namespace);
  		if ($this->groupDatas[$namespace] === null) {
  			$this->groupDatas[$namespace] = $this->dbtextDao->getGroupData($namespace);
  			$this->writeToAppCache($this->groupDatas[$namespace]);
  		}
  		
  		if ($this->moduleConfig->isModifyOnRequest()) {
  			$this->groupDatas[$namespace]->registerListener($this);
  		}
  
  		return $this->groupDatas[$namespace];
  	}
docs: {@see GroupData} stored in cache or database can be found.
  
  @param string $namespace
  @return GroupData