refactor: resolve SonarCloud quick-win code smells

library/src/main/java/dev/andstuff/kraken/api/KrakenAPI.java

@@ -247,6 +247,7 @@
  * @see <a href="https://docs.kraken.com/rest/">Kraken REST API documentation</a>
  */
 @Builder(toBuilder = true)
+@SuppressWarnings("java:S6539")
 public class KrakenAPI {
 
     private final KrakenCredentials credentials;

library/src/main/java/dev/andstuff/kraken/api/endpoint/account/params/WalletAccountsParams.java

@@ -16,7 +16,6 @@ public class WalletAccountsParams extends PostParams {
 
     @Override
     protected Map<String, String> params() {
-        Map<String, String> params = new HashMap<>();
-        return params;
+        return new HashMap<>();
     }
 }

library/src/main/java/dev/andstuff/kraken/api/endpoint/funding/response/DepositLimitDeserializer.java

@@ -26,7 +26,7 @@ public DepositLimit deserialize(JsonParser parser, DeserializationContext contex
             try {
                 return new DepositLimit(new BigDecimal(parser.getText()), false);
             }
-            catch (NumberFormatException e) {
+            catch (NumberFormatException _) {
                 return context.reportInputMismatch(DepositLimit.class, "Expected a decimal deposit limit or false");
             }
         }

library/src/main/java/dev/andstuff/kraken/api/endpoint/fundingbeta/FundingBetaParams.java

@@ -31,6 +31,7 @@ public Map<String, String> toMap() {
      *
      * @return the body parameters, or {@code null} for an endpoint sending no body
      */
+    @SuppressWarnings("java:S1168")
     protected Map<String, Object> body() {
         return null;
     }

library/src/main/java/dev/andstuff/kraken/api/endpoint/fundingbeta/params/CreateFundingWithdrawalParams.java

@@ -85,7 +85,10 @@ protected Map<String, Object> body() {
         body.put("scope", scope.json());
         body.put("address_id", addressId);
         body.put("amount", rebasable("asset_amount", amount.json()));
-        putIfNonNull(body, "fee", fee());
+        Map<String, Object> fee = fee();
+        if (!fee.isEmpty()) {
+            body.put("fee", fee);
+        }
         putIfNonNull(body, "expected_address", expectedAddress);
         return body;
     }
@@ -95,7 +98,7 @@ private Map<String, Object> fee() {
             throw new IllegalArgumentException("Specify at most one of withdrawalFeeToken or maxFee");
         }
         if (withdrawalFeeToken == null && maxFee == null && feeIncluded == null) {
-            return null;
+            return Map.of();
         }
         if (feeIncluded == null) {
             throw new IllegalArgumentException("feeIncluded is required with withdrawalFeeToken or maxFee");

library/src/main/java/dev/andstuff/kraken/api/endpoint/fundingbeta/response/LimitValueDeserializer.java

@@ -25,7 +25,7 @@ public LimitValue deserialize(JsonParser parser, DeserializationContext context)
             try {
                 return new LimitValue(Long.valueOf(parser.getText()), null);
             }
-            catch (NumberFormatException e) {
+            catch (NumberFormatException _) {
                 return context.reportInputMismatch(LimitValue.class, "Expected a count or limit amounts");
             }
         }

library/src/main/java/dev/andstuff/kraken/api/endpoint/priv/JsonPostParams.java

@@ -23,7 +23,7 @@ public abstract class JsonPostParams extends PostParams {
     @Override
     protected String encode(Map<String, Object> params) {
         String nonce = (String) params.get("nonce");
-        BigInteger numericNonce = nonce != null && nonce.matches("0|[1-9][0-9]{0,19}") ? new BigInteger(nonce) : null;
+        BigInteger numericNonce = nonce != null && nonce.matches("0|[1-9]\\d{0,19}") ? new BigInteger(nonce) : null;
         if (numericNonce == null || numericNonce.bitLength() > 64) {
             throw new IllegalStateException("%s requires KrakenNonceGenerator to return an unsigned 64-bit integer in canonical decimal form".formatted(getClass().getSimpleName()));
         }

library/src/main/java/dev/andstuff/kraken/api/endpoint/priv/PostParams.java

@@ -20,6 +20,7 @@ public abstract class PostParams {
      *
      * @return the POST parameters
      */
+    @SuppressWarnings("java:S1452")
     protected abstract Map<String, ?> params();
 
     private String nonce;

library/src/main/java/dev/andstuff/kraken/api/rest/DefaultKrakenRestRequester.java

@@ -33,6 +33,7 @@
 @Slf4j
 public class DefaultKrakenRestRequester implements KrakenRestRequester {
 
+    private static final String CONTENT_TYPE = "Content-Type";
     private static final ObjectMapper OBJECT_MAPPER;
 
     static {
@@ -91,7 +92,7 @@ public <T> T execute(PrivateEndpoint<T> endpoint, KrakenCredentials credentials,
             log.info("Fetching private endpoint: {}", connection.getURL());
             connection.addRequestProperty("API-Key", credentials.getKey());
             connection.addRequestProperty("API-Sign", credentials.sign(connection.getURL(), nonce, postData));
-            connection.addRequestProperty("Content-Type", endpoint.getContentType());
+            connection.addRequestProperty(CONTENT_TYPE, endpoint.getContentType());
             connection.setDoOutput(true);
 
             try (OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream())) {
@@ -124,7 +125,7 @@ public <T> T execute(FundingBetaEndpoint<T> endpoint, KrakenCredentials credenti
             connection.addRequestProperty("API-Nonce", nonce);
 
             if (!body.isEmpty()) {
-                connection.addRequestProperty("Content-Type", endpoint.getContentType());
+                connection.addRequestProperty(CONTENT_TYPE, endpoint.getContentType());
                 connection.setDoOutput(true);
 
                 try (OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream(), StandardCharsets.UTF_8)) {
@@ -147,7 +148,7 @@ private <T> HttpsURLConnection createHttpsConnection(Endpoint<T> endpoint) throw
     }
 
     private static <T> T parseResponse(HttpsURLConnection connection, Endpoint<T> endpoint) throws IOException {
-        String contentType = connection.getHeaderField("Content-Type");
+        String contentType = connection.getHeaderField(CONTENT_TYPE);
         if ("application/json".equals(contentType)) {
             JavaType krakenResponseType = endpoint.wrappedResponseType(OBJECT_MAPPER.getTypeFactory());
             KrakenResponse<T> response = OBJECT_MAPPER.readValue(connection.getInputStream(), krakenResponseType);
@@ -169,7 +170,7 @@ private static <T> T parseFundingResponse(HttpsURLConnection connection, Funding
             throw new KrakenException(List.of("HTTP %d %s".formatted(status, readErrorBody(connection)).strip()));
         }
 
-        String contentType = connection.getHeaderField("Content-Type");
+        String contentType = connection.getHeaderField(CONTENT_TYPE);
         if (contentType == null || !contentType.startsWith("application/json")) {
             throw new IllegalStateException("Unsupported HTTP Content-Type");
         }

library/src/test/java/dev/andstuff/kraken/api/KrakenAPIAccountTest.java

@@ -125,7 +125,7 @@ void should_route_accountBalance_defaults_when_called() {
     void should_reject_accountBalance_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.accountBalance()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::accountBalance).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -156,7 +156,7 @@ void should_route_extendedBalance_defaults_when_called() {
     void should_reject_extendedBalance_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.extendedBalance()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::extendedBalance).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -189,7 +189,7 @@ void should_route_creditLines_defaults_when_called() {
     void should_reject_creditLines_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.creditLines()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::creditLines).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -222,7 +222,7 @@ void should_route_tradeBalance_defaults_when_called() {
     void should_reject_tradeBalance_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.tradeBalance()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::tradeBalance).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -255,7 +255,7 @@ void should_route_openOrders_defaults_when_called() {
     void should_reject_openOrders_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.openOrders()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::openOrders).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -288,7 +288,7 @@ void should_route_closedOrders_defaults_when_called() {
     void should_reject_closedOrders_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.closedOrders()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::closedOrders).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -342,7 +342,7 @@ void should_route_orderAmends_defaults_when_called() {
     void should_reject_orderAmends_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.orderAmends()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::orderAmends).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -375,7 +375,7 @@ void should_route_tradesHistory_defaults_when_called() {
     void should_reject_tradesHistory_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.tradesHistory()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::tradesHistory).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -427,7 +427,7 @@ void should_route_openPositions_defaults_when_called() {
     void should_reject_openPositions_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.openPositions()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::openPositions).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -460,7 +460,7 @@ void should_route_tradeVolume_defaults_when_called() {
     void should_reject_tradeVolume_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.tradeVolume()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::tradeVolume).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -493,7 +493,7 @@ void should_route_apiKeyInfo_defaults_when_called() {
     void should_reject_apiKeyInfo_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.apiKeyInfo()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::apiKeyInfo).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -526,7 +526,7 @@ void should_route_walletAccounts_defaults_when_called() {
     void should_reject_walletAccounts_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.walletAccounts()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::walletAccounts).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 

library/src/test/java/dev/andstuff/kraken/api/KrakenAPIEarnTest.java

@@ -71,7 +71,7 @@ void should_route_earnStrategies_defaults_when_called() {
     void should_reject_earnStrategies_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.earnStrategies()).isInstanceOf(IllegalStateException.class).hasMessageContaining("Earn/Strategies");
+        assertThatThrownBy(unit::earnStrategies).isInstanceOf(IllegalStateException.class).hasMessageContaining("Earn/Strategies");
         verifyNoInteractions(requester);
     }
 
@@ -104,7 +104,7 @@ void should_route_earnAllocations_defaults_when_called() {
     void should_reject_earnAllocations_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.earnAllocations()).isInstanceOf(IllegalStateException.class).hasMessageContaining("Earn/Allocations");
+        assertThatThrownBy(unit::earnAllocations).isInstanceOf(IllegalStateException.class).hasMessageContaining("Earn/Allocations");
         verifyNoInteractions(requester);
     }
 

library/src/test/java/dev/andstuff/kraken/api/KrakenAPIFundingTest.java

@@ -133,7 +133,7 @@ void should_route_depositStatus_defaults_when_called() {
     void should_reject_depositStatus_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.depositStatus()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::depositStatus).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -164,7 +164,7 @@ void should_route_withdrawalMethods_defaults_when_called() {
     void should_reject_withdrawalMethods_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.withdrawalMethods()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::withdrawalMethods).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -195,7 +195,7 @@ void should_route_withdrawalAddresses_defaults_when_called() {
     void should_reject_withdrawalAddresses_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.withdrawalAddresses()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::withdrawalAddresses).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 
@@ -272,7 +272,7 @@ void should_route_withdrawalStatus_defaults_when_called() {
     void should_reject_withdrawalStatus_when_credentials_are_missing() {
         KrakenAPI unit = new KrakenAPI(null, nonceGenerator, requester);
 
-        assertThatThrownBy(() -> unit.withdrawalStatus()).isInstanceOf(IllegalStateException.class);
+        assertThatThrownBy(unit::withdrawalStatus).isInstanceOf(IllegalStateException.class);
         verifyNoInteractions(requester);
     }
 

library/src/test/java/dev/andstuff/kraken/api/endpoint/account/LedgerInfoEndpointTest.java

@@ -105,7 +105,7 @@ void should_deserialize_typed_response_when_reading_kraken_fixture() throws Exce
         assertThat(result.size()).isEqualTo(2);
         assertThat(result.hasNext()).isFalse();
         assertThat(result.asList()).extracting(LedgerEntry::id).containsExactlyInAnyOrder("L4UESK-KG3EQ-UFO4T5", "LMKZCZ-Z3GVL-CXKK4H");
-        assertThat(result.entries().get("L4UESK-KG3EQ-UFO4T5")).isEqualTo(new LedgerEntry(null, "TJKLXF-PGMUI-4NTLXU",
+        assertThat(result.entries()).containsEntry("L4UESK-KG3EQ-UFO4T5", new LedgerEntry(null, "TJKLXF-PGMUI-4NTLXU",
                 Instant.ofEpochSecond(1688464484L, 178_700_000L), LedgerEntry.Type.TRADE, "", "currency", null, "ZGBP", null,
                 new BigDecimal("-24.5000"), new BigDecimal("0.0490"), new BigDecimal("459567.9171")));
         assertThat(result.entries().get("L4UESK-KG3EQ-UFO4T5").netAmount()).isEqualByComparingTo("-24.5490");

library/src/test/java/dev/andstuff/kraken/api/endpoint/account/QueryOrdersEndpointTest.java

@@ -51,7 +51,9 @@ void should_encode_all_options_when_supplied() {
 
     @Test
     void should_reject_missing_transactionIds_when_building_parameters() {
-        assertThatThrownBy(() -> QueryOrdersParams.builder().build()).isInstanceOf(NullPointerException.class).hasMessageContaining("transactionIds");
+        QueryOrdersParams.QueryOrdersParamsBuilder builder = QueryOrdersParams.builder();
+
+        assertThatThrownBy(builder::build).isInstanceOf(NullPointerException.class).hasMessageContaining("transactionIds");
     }
 
     @Test

library/src/test/java/dev/andstuff/kraken/api/endpoint/account/QueryTradesEndpointTest.java

@@ -48,7 +48,9 @@ void should_encode_all_options_when_supplied() {
 
     @Test
     void should_reject_missing_transactionIds_when_building_parameters() {
-        assertThatThrownBy(() -> QueryTradesParams.builder().build()).isInstanceOf(NullPointerException.class).hasMessageContaining("transactionIds");
+        QueryTradesParams.QueryTradesParamsBuilder builder = QueryTradesParams.builder();
+
+        assertThatThrownBy(builder::build).isInstanceOf(NullPointerException.class).hasMessageContaining("transactionIds");
     }
 
     @Test

library/src/test/java/dev/andstuff/kraken/api/endpoint/account/TradeVolumeEndpointTest.java

@@ -128,7 +128,7 @@ void should_preserve_unsigned_nonce_when_encoding_its_maximum_value() throws Exc
     }
 
     @Test
-    void should_reuse_json_encoding_when_parameters_are_encoded_directly() throws Exception {
+    void should_reuse_json_encoding_when_parameters_are_encoded_directly() {
         TradeVolumeParams params = TradeVolumeParams.builder().pairs(List.of("XBTUSD")).feeSchedule(true).build();
         TradeVolumeEndpoint unit = new TradeVolumeEndpoint(params);
 

library/src/test/java/dev/andstuff/kraken/api/endpoint/funding/CancelWithdrawalEndpointTest.java

@@ -44,12 +44,16 @@ void should_encode_all_options_when_supplied() {
 
     @Test
     void should_reject_missing_asset_when_building_parameters() {
-        assertThatThrownBy(() -> CancelWithdrawalParams.builder().referenceId("id +/&=").build()).isInstanceOf(NullPointerException.class).hasMessageContaining("asset");
+        CancelWithdrawalParams.CancelWithdrawalParamsBuilder builder = CancelWithdrawalParams.builder().referenceId("id +/&=");
+
+        assertThatThrownBy(builder::build).isInstanceOf(NullPointerException.class).hasMessageContaining("asset");
     }
 
     @Test
     void should_reject_missing_referenceId_when_building_parameters() {
-        assertThatThrownBy(() -> CancelWithdrawalParams.builder().asset("id +/&=").build()).isInstanceOf(NullPointerException.class).hasMessageContaining("referenceId");
+        CancelWithdrawalParams.CancelWithdrawalParamsBuilder builder = CancelWithdrawalParams.builder().asset("id +/&=");
+
+        assertThatThrownBy(builder::build).isInstanceOf(NullPointerException.class).hasMessageContaining("referenceId");
     }
 
     @Test

library/src/test/java/dev/andstuff/kraken/api/endpoint/funding/DepositAddressesEndpointTest.java

@@ -51,12 +51,16 @@ void should_encode_all_options_when_supplied() {
 
     @Test
     void should_reject_missing_asset_when_building_parameters() {
-        assertThatThrownBy(() -> DepositAddressesParams.builder().method("id +/&=").build()).isInstanceOf(NullPointerException.class).hasMessageContaining("asset");
+        DepositAddressesParams.DepositAddressesParamsBuilder builder = DepositAddressesParams.builder().method("id +/&=");
+
+        assertThatThrownBy(builder::build).isInstanceOf(NullPointerException.class).hasMessageContaining("asset");
     }
 
     @Test
     void should_reject_missing_method_when_building_parameters() {
-        assertThatThrownBy(() -> DepositAddressesParams.builder().asset("id +/&=").build()).isInstanceOf(NullPointerException.class).hasMessageContaining("method");
+        DepositAddressesParams.DepositAddressesParamsBuilder builder = DepositAddressesParams.builder().asset("id +/&=");
+
+        assertThatThrownBy(builder::build).isInstanceOf(NullPointerException.class).hasMessageContaining("method");
     }
 
     @Test

library/src/test/java/dev/andstuff/kraken/api/endpoint/funding/DepositMethodsEndpointTest.java

@@ -49,7 +49,9 @@ void should_encode_all_options_when_supplied() {
 
     @Test
     void should_reject_missing_asset_when_building_parameters() {
-        assertThatThrownBy(() -> DepositMethodsParams.builder().build()).isInstanceOf(NullPointerException.class).hasMessageContaining("asset");
+        DepositMethodsParams.DepositMethodsParamsBuilder builder = DepositMethodsParams.builder();
+
+        assertThatThrownBy(builder::build).isInstanceOf(NullPointerException.class).hasMessageContaining("asset");
     }
 
     @Test