code: public boolean isExpectedNonce (@Nullable final String sNonceToCheck)
    {
      final String sThisNonce = getNonce ();
      return StringHelper.hasText (sThisNonce) &&
             sThisNonce.equals (sNonceToCheck) &&
             CSRFManager.getInstance ().isValidNonce (sNonceToCheck);
    }
docs: Check if the passed nonce is the expected one for this session.
  
  @param sNonceToCheck
  The nonce to be checked. May be <code>null</code>.
  @return <code>true</code> if the nonce is as expected, <code>false</code>
  otherwise.