//JAVA TO C# CONVERTER TODO TASK: Most Java annotations will not have direct .NET equivalent attributes:
//ORIGINAL LINE: @ImmutableConstructor private FxRateId(com.opengamma.strata.basics.currency.CurrencyPair currencyPair, ObservableSource observableSource)
private FxRateId(CurrencyPair currencyPair, ObservableSource observableSource)
{
ArgChecker.notNull(currencyPair, "currencyPair");
ArgChecker.notNull(observableSource, "observableSource");
this.pair = currencyPair.toConventional();
this.observableSource = observableSource;
}
/// <summary>
/// Returns a key identifying the market quote for an observable FX rate.
/// <para>
/// If the FX rate is not observable in the market an empty optional is returned.
/// </para>
/// <para>
/// It is possible the quote is for the rate of the inverse of the currency pair. This does not matter as
/// the market data system ensures that the correct rate is always provided regardless of which way round
/// the pair is quoted.
///
/// </para>
/// </summary>
/// <param name="currencyPair"> the currency pair </param>
/// <returns> a key identifying the market quote for the rate if it is observable in the market </returns>
public Optional <QuoteId> getObservableRateKey(CurrencyPair currencyPair)
{
QuoteId quoteId = observableRates.get(currencyPair.toConventional());
return(Optional.ofNullable(quoteId));
}