code: private void validateClient(Client client) throws RegistrationException {
          Set<Contract> contracts = client.getContracts();
          if (contracts.isEmpty()) {
              throw new NoContractFoundException(Messages.i18n.format("ESRegistry.NoContracts")); //$NON-NLS-1$
          }
          for (Contract contract : contracts) {
              validateContract(contract);
          }
      }
docs: Validate that the client should be registered.
  @param client