multitenant.php

<?php

// [..snip..]

        $this->participantRepositoryFactory
            ->forTenant(
                $this->getTenantIdFromOAuthClient($client)
            )
            ->persist(
                $participant
            );

// [..snip..]

    /**
     * Get a TenantId instance from an authenticated OAuth client.
     *
     * @param OAuthClient $client
     *
     * @return TenantId
     */
    private function getTenantIdFromOAuthClient(OAuthClient $client)
    {
        $tenantId = $client->getValueOfRelation(OAuthClient::RELATION_SECURITY_USER);
        if ($tenantId === null) {
            throw new RuntimeException(
                strtr(
                    'Cannot find a "{relation}" relation for OAuth client "{name}".',
                    array(
                        '{relation}' => OAuthClient::RELATION_SECURITY_USER,
                        '{name}' => $client->getName(),
                    )
                ),
                1426678183
            );
        }

        return new TenantId($tenantId);
    }