docs: @Nonnull
    public CSP2SourceList addNonce (@Nonnull @Nonempty final String sNonceBase64Value)
    {
      ValueEnforcer.notEmpty (sNonceBase64Value, "NonceBase64Value");
  
      m_aList.add (NONCE_PREFIX + sNonceBase64Value + NONCE_SUFFIX);
      return this;
    }