code: protected function resolveOptions(array $options)
      {
          if ($this->optionsResolved) {
              return;
          }
  
          $this->optionsResolver->clear();
          $this->optionsResolver->setRequired(
              array(
                  'blockname',
              )
          );
  
          parent::resolveOptions($options);
          $this->optionsResolved = true;
      }
docs: Defines the common required options by a block manager
  
  @param array $options