### Question:
DataPayload { @JsonIgnore public boolean isValidPayload() { fixNullValues(); return notContainsNullElements(users) && notContainsNullElements(accounts) && notContainsNullElements(balancesList) && notContainsNullElements(payments); }  @JsonIgnore boolean isValidPayload(); @JsonIgnore Map<String, AccountDetailsTO> getAccountByIban(); @JsonIgnore Map<String, AccountBalance> getBalancesByIban(); @JsonIgnore DataPayload updatePayload(BiFunction<DataPayload, String, String> ibanGenerator, String branch, Currency currency, boolean generatePayments);  }### Answer:
@Test void isValidPayload_valid() { DataPayload data = getData(false, false, false); boolean result = data.isValidPayload(); assertTrue(result); }
@Test void isValidPayloadValid_emptyUsers() { DataPayload data = getData(true, false, false); boolean result = data.isValidPayload(); assertTrue(result); }
@Test void isValidPayloadValid_nullAccounts() { DataPayload data = getData(false, true, false); boolean result = data.isValidPayload(); assertTrue(result); assertNotNull(data.getAccounts()); }
@Test void isValidPayloadValid_nullElementBalance() { DataPayload data = getData(false, false, true); boolean result = data.isValidPayload(); assertFalse(result); }