code: @Nonnull
    public CSP2SourceList addNonce (@Nonnull @Nonempty final byte [] aNonceValue)
    {
      ValueEnforcer.notEmpty (aNonceValue, "NonceValue");
      return addNonce (Base64.safeEncodeBytes (aNonceValue));
    }
docs: Add the provided nonce value. The {@value #NONCE_PREFIX} and
  {@link #NONCE_SUFFIX} are added automatically. The byte array is
  automatically Bas64 encoded!
  
  @param aNonceValue
  The plain nonce value. May not be <code>null</code>.
  @return this for chaining