code: public function isMappedIdentity($objectIdentifier, $objectType, $adapterName)
      {
          $identities = $this->findBy([
              'objectIdentifier' => $objectIdentifier,
              'objectType' => $objectType,
          ]);
  
          $otherIdentities = array_filter($identities, function (Identity $identity) use ($adapterName) {
              return $identity->getAdapterName() !== $adapterName;
          });
  
          if (empty($otherIdentities)) {
              return false;
          }
  
          return true;
      }
docs: {@inheritdoc}