### Question:
CurrencyValue implements Serializable { public static boolean isNullOrZero(CurrencyValue value) { return value == null || value.getValue() == null || value.isZero(); }  abstract String getCurrency(); abstract BigDecimal getValue(); boolean isZero(); @Override String toString(); static CurrencyValue fromValue(CurrencyValue currencyValue, String targetCurrency, ExchangeRateProvider exchangeRateManager); static CurrencyValue fromValue(ExchangeBasedCurrencyValue value, String targetCurrency, ExchangeRateProvider exchangeRateManager); static CurrencyValue fromValue(ExactCurrencyValue value, String targetCurrency, ExchangeRateProvider exchangeRateManager); static boolean isNullOrZero(CurrencyValue value); boolean isBtc(); boolean isFiat(); BitcoinValue getBitcoinValue(ExchangeRateProvider exchangeRateManager); CurrencyValue add(CurrencyValue other, ExchangeRateProvider exchangeRateProvider); Bitcoins getAsBitcoin(ExchangeRateProvider exchangeRateManager); abstract ExactCurrencyValue getExactValue(); CurrencyValue getExactValueIfPossible(); @Override boolean equals(Object o); @Override int hashCode(); static Optional<ExactCurrencyValue> checkCurrencyAmount(CurrencyValue amount, String currency); static final String BTC; }### Answer:
@Test public void testIsNullOrZero() throws Exception { assertFalse(CurrencyValue.isNullOrZero(ExactBitcoinValue.from(BigDecimal.ONE))); assertFalse(CurrencyValue.isNullOrZero(ExactCurrencyValue.from(BigDecimal.ONE, "EUR"))); assertTrue(CurrencyValue.isNullOrZero(null)); assertTrue(CurrencyValue.isNullOrZero(ExactCurrencyValue.from(null, "EUR"))); assertTrue(CurrencyValue.isNullOrZero(ExactBitcoinValue.from(0L))); assertTrue(CurrencyValue.isNullOrZero(ExactBitcoinValue.ZERO)); }