private Tenant getExistingTenant(HttpRequest request) {
        TenantName tenantName = Utils.getTenantNameFromSessionRequest(request);
        Utils.checkThatTenantExists(tenantRepository, tenantName);
        return tenantRepository.getTenant(tenantName);
    }
A handler that prepares a session given by an id in the request. v2 of application API

@author hmusum
configserver/src/main/java/com/yahoo/vespa/config/server/http/v2/SessionPrepareHandler.java