Require "final" for parameters when possible

adapters/http-vertx-base/src/main/java/org/eclipse/hono/adapter/http/HonoBasicAuthHandler.java

@@ -49,7 +49,7 @@ public HonoBasicAuthHandler(final AuthProvider authProvider, final String realm)
     }
 
     @Override
-    public void parseCredentials(RoutingContext context, Handler<AsyncResult<JsonObject>> handler) {
+    public void parseCredentials(final RoutingContext context, final Handler<AsyncResult<JsonObject>> handler) {
 
       parseAuthorization(context, false, parseAuthorization -> {
         if (parseAuthorization.failed()) {
@@ -83,11 +83,12 @@ public void parseCredentials(RoutingContext context, Handler<AsyncResult<JsonObj
     }
 
     @Override
-    protected String authenticateHeader(RoutingContext context) {
+    protected String authenticateHeader(final RoutingContext context) {
       return "Basic realm=\"" + realm + "\"";
     }
 
-    protected final void parseAuthorization(RoutingContext ctx, boolean optional, Handler<AsyncResult<String>> handler) {
+    protected final void parseAuthorization(final RoutingContext ctx, final boolean optional,
+            final Handler<AsyncResult<String>> handler) {
 
         final HttpServerRequest request = ctx.request();
         final String authorization = request.headers().get(HttpHeaders.AUTHORIZATION);

adapters/http-vertx/src/main/java/org/eclipse/hono/adapter/http/vertx/VertxBasedHttpProtocolAdapter.java

@@ -90,7 +90,7 @@ protected void addRoutes(final Router router) {
         }
     }
 
-    private void addTelemetryApiRoutes(final Router router, Handler<RoutingContext> basicAuthHandler) {
+    private void addTelemetryApiRoutes(final Router router, final Handler<RoutingContext> basicAuthHandler) {
 
         // support CORS headers for PUTing telemetry
         router.routeWithRegex("\\/telemetry\\/[^\\/]+\\/.*").handler(CorsHandler.create(getConfig().getCorsAllowedOrigin())
@@ -125,7 +125,7 @@ private void addTelemetryApiRoutes(final Router router, Handler<RoutingContext>
                 .handler(ctx -> uploadTelemetryMessage(ctx, getTenantParam(ctx), getDeviceIdParam(ctx)));
     }
 
-    private void addEventApiRoutes(final Router router, Handler<RoutingContext> basicAuthHandler) {
+    private void addEventApiRoutes(final Router router, final Handler<RoutingContext> basicAuthHandler) {
 
         // support CORS headers for PUTing events
         router.routeWithRegex("\\/event\\/[^\\/]+\\/.*").handler(CorsHandler.create(getConfig().getCorsAllowedOrigin())

adapters/kura/src/test/java/org/eclipse/hono/adapter/kura/KuraProtocolAdapterTest.java

@@ -197,7 +197,7 @@ public void testMapTopicMapsKuraDataMessagesToEventApi(final TestContext ctx) {
         assertThat(context.contentType(), is(config.getDataMsgContentType()));
     }
 
-    private void assertAddress(final ResourceIdentifier address, final String endpoint, String tenantId, final String deviceId) {
+    private void assertAddress(final ResourceIdentifier address, final String endpoint, final String tenantId, final String deviceId) {
         assertThat(address.getEndpoint(), is(endpoint));
         assertThat(address.getTenantId(), is(tenantId));
         assertThat(address.getResourceId(), is(deviceId));

adapters/mqtt-vertx-base/src/test/java/org/eclipse/hono/adapter/mqtt/AbstractVertxBasedMqttProtocolAdapterTest.java

@@ -552,7 +552,7 @@ private void forceClientMocksToConnected() {
         when(credentialsServiceClient.isConnected()).thenReturn(Future.succeededFuture());
     }
 
-    private MqttEndpoint getMqttEndpointAuthenticated(String username, String password) {
+    private MqttEndpoint getMqttEndpointAuthenticated(final String username, final String password) {
         final MqttEndpoint endpoint = mock(MqttEndpoint.class);
         when(endpoint.auth()).thenReturn(new MqttAuth(username, password));
         return endpoint;

client/src/main/java/org/eclipse/hono/client/impl/AbstractSender.java

@@ -229,16 +229,18 @@ public final Future<ProtonDelivery> send(final String deviceId, final Map<String
     }
 
     @Override
-    public final Future<ProtonDelivery> send(String deviceId, Map<String, ?> properties, String payload, String contentType,
-            String registrationAssertion, Handler<Void> capacityAvailableHandler) {
+    public final Future<ProtonDelivery> send(final String deviceId, final Map<String, ?> properties,
+            final String payload, final String contentType, final String registrationAssertion,
+            final Handler<Void> capacityAvailableHandler) {
         Objects.requireNonNull(payload);
         final Charset charset = getCharsetForContentType(Objects.requireNonNull(contentType));
         return send(deviceId, properties, payload.getBytes(charset), contentType, registrationAssertion, capacityAvailableHandler);
     }
 
     @Override
-    public final Future<ProtonDelivery> send(String deviceId, Map<String, ?> properties, byte[] payload, String contentType,
-            String registrationAssertion, Handler<Void> capacityAvailableHandler) {
+    public final Future<ProtonDelivery> send(final String deviceId, final Map<String, ?> properties,
+            final byte[] payload, final String contentType, final String registrationAssertion,
+            final Handler<Void> capacityAvailableHandler) {
 
         Objects.requireNonNull(deviceId);
         Objects.requireNonNull(payload);

client/src/main/java/org/eclipse/hono/client/impl/EventSenderImpl.java

@@ -152,7 +152,7 @@ protected Future<ProtonDelivery> sendMessage(final Message message) {
      * @throws NullPointerException if the message is {@code null}.
      */
     @Override
-    public Future<ProtonDelivery> sendAndWaitForOutcome(Message message) {
+    public Future<ProtonDelivery> sendAndWaitForOutcome(final Message message) {
 
         return sendMessageAndWaitForOutcome(message);
     }

client/src/test/java/org/eclipse/hono/client/impl/HonoClientImplTest.java

@@ -556,7 +556,7 @@ public void setExpectedSucceedingConnectionAttempts(final int attempts) {
             expectedSucceedingConnectionAttempts = new CountDownLatch(attempts);
         }
 
-        public boolean await(long timeout, TimeUnit unit) {
+        public boolean await(final long timeout, final TimeUnit unit) {
             try {
                 return expectedSucceedingConnectionAttempts.await(timeout, unit);
             } catch (InterruptedException e) {

core/src/main/java/org/eclipse/hono/config/ClientConfigProperties.java

@@ -242,7 +242,7 @@ public final String getAmqpHostname() {
      * 
      * @param amqpHostname The host name to set.
      */
-    public final void setAmqpHostname(String amqpHostname) {
+    public final void setAmqpHostname(final String amqpHostname) {
         this.amqpHostname = amqpHostname;
     }
 
@@ -367,7 +367,7 @@ public final boolean isHostnameVerificationRequired() {
      * 
      * @param hostnameVerificationRequired {@code true} if the host name should be matched.
      */
-    public final void setHostnameVerificationRequired(boolean hostnameVerificationRequired) {
+    public final void setHostnameVerificationRequired(final boolean hostnameVerificationRequired) {
         this.hostnameVerificationRequired = hostnameVerificationRequired;
     }
 
@@ -400,7 +400,7 @@ public final boolean isTlsEnabled() {
      * 
      * @param enabled {@code true} if the server identity should be verified.
      */
-    public final void setTlsEnabled(boolean enabled) {
+    public final void setTlsEnabled(final boolean enabled) {
         this.tlsEnabled = enabled;
     }
 }

core/src/main/java/org/eclipse/hono/util/CacheDirective.java

@@ -61,7 +61,7 @@ public static CacheDirective noCacheDirective() {
      * @param directive The directive to parse.
      * @return The cache directive or {@code null} if the directive cannot be parsed.
      */
-    public static CacheDirective from(String directive) {
+    public static CacheDirective from(final String directive) {
 
         if (directive == null) {
             return null;

core/src/main/java/org/eclipse/hono/util/EndpointType.java

@@ -24,7 +24,7 @@ public enum EndpointType {
      * @return The enum literal of the endpoint type. Returns {@link #UNKNOWN} if it cannot find the endpoint type.
      *         Never returns {@code null}.
      */
-    public static EndpointType fromString(String name) {
+    public static EndpointType fromString(final String name) {
         switch (name) {
         case TelemetryConstants.TELEMETRY_ENDPOINT:
         case TelemetryConstants.TELEMETRY_ENDPOINT_SHORT:

core/src/main/java/org/eclipse/hono/util/JwtHelper.java

@@ -192,7 +192,7 @@ public static final Date getExpiration(final String token) {
 
                 @SuppressWarnings("rawtypes")
                 @Override
-                public Key resolveSigningKey(JwsHeader header, Claims claims) {
+                public Key resolveSigningKey(final JwsHeader header, final Claims claims) {
                     Date exp = claims.getExpiration();
                     if (exp != null) {
                         result.set(exp);

core/src/main/java/org/eclipse/hono/util/TriTuple.java

@@ -26,7 +26,7 @@ public final class TriTuple<A, B, C> {
     private final B two;
     private final C three;
 
-    private TriTuple(final A one, B two, C three) {
+    private TriTuple(final A one, final B two, final C three) {
 
         if (one == null && two == null && three == null) {
             throw new IllegalArgumentException("at least one argument must be non-null");
@@ -91,7 +91,7 @@ public int hashCode() {
      */
     @SuppressWarnings("rawtypes")
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(final Object obj) {
         if (this == obj) {
             return true;
         }

core/src/test/java/org/eclipse/hono/util/StringsTest.java

@@ -30,7 +30,7 @@ private static class Mock {
 
         private String value;
 
-        Mock(String value) {
+        Mock(final String value) {
             this.value = value;
         }
 

jmeter/src/main/java/org/eclipse/hono/jmeter/client/AbstractClient.java

@@ -1,57 +1,57 @@
-package org.eclipse.hono.jmeter.client;
-
-import io.vertx.core.Future;
-import io.vertx.core.Vertx;
-import io.vertx.core.VertxOptions;
-import io.vertx.core.dns.AddressResolverOptions;
-import io.vertx.proton.ProtonClientOptions;
-
-/**
- * Base class for implementing JMeter samplers connecting to Hono.
- *
- */
-public abstract class AbstractClient {
-
-    static final int    DEFAULT_CONNECT_TIMEOUT_MILLIS            = 1000;
-    static final int    DEFAULT_ADDRESS_RESOLUTION_TIMEOUT_MILLIS = 2000;
-    static final String TIME_STAMP_VARIABLE                       = "timeStamp";
-
-    /**
-     * The vert.x instance to use for connecting to Hono.
-     */
-    protected final Vertx vertx;
-
-    /**
-     * Creates a new client.
-     */
-    protected AbstractClient() {
-        vertx = vertx();
-    }
-
-    final Vertx vertx() {
-        VertxOptions options = new VertxOptions()
-                .setWarningExceptionTime(1500000000)
-                .setAddressResolverOptions(new AddressResolverOptions()
-                        .setCacheNegativeTimeToLive(0) // discard failed DNS lookup results immediately
-                        .setCacheMaxTimeToLive(0) // support DNS based service resolution
-                        .setRotateServers(true)
-                        .setQueryTimeout(DEFAULT_ADDRESS_RESOLUTION_TIMEOUT_MILLIS));
-        return Vertx.vertx(options);
-    }
-
-    final ProtonClientOptions getClientOptions(int reconnectAttempts) {
-        return new ProtonClientOptions().setConnectTimeout(DEFAULT_CONNECT_TIMEOUT_MILLIS)
-                .setReconnectAttempts(reconnectAttempts);
-    }
-
-    /**
-     * Closes the vert.x instance.
-     * 
-     * @return A future that will succeed once the instance is closed.
-     */
-    protected final Future<Void> closeVertx() {
-        final Future<Void> result = Future.future();
-        vertx.close(result.completer());
-        return result;
-    }
-}
+package org.eclipse.hono.jmeter.client;
+
+import io.vertx.core.Future;
+import io.vertx.core.Vertx;
+import io.vertx.core.VertxOptions;
+import io.vertx.core.dns.AddressResolverOptions;
+import io.vertx.proton.ProtonClientOptions;
+
+/**
+ * Base class for implementing JMeter samplers connecting to Hono.
+ *
+ */
+public abstract class AbstractClient {
+
+    static final int    DEFAULT_CONNECT_TIMEOUT_MILLIS            = 1000;
+    static final int    DEFAULT_ADDRESS_RESOLUTION_TIMEOUT_MILLIS = 2000;
+    static final String TIME_STAMP_VARIABLE                       = "timeStamp";
+
+    /**
+     * The vert.x instance to use for connecting to Hono.
+     */
+    protected final Vertx vertx;
+
+    /**
+     * Creates a new client.
+     */
+    protected AbstractClient() {
+        vertx = vertx();
+    }
+
+    final Vertx vertx() {
+        VertxOptions options = new VertxOptions()
+                .setWarningExceptionTime(1500000000)
+                .setAddressResolverOptions(new AddressResolverOptions()
+                        .setCacheNegativeTimeToLive(0) // discard failed DNS lookup results immediately
+                        .setCacheMaxTimeToLive(0) // support DNS based service resolution
+                        .setRotateServers(true)
+                        .setQueryTimeout(DEFAULT_ADDRESS_RESOLUTION_TIMEOUT_MILLIS));
+        return Vertx.vertx(options);
+    }
+
+    final ProtonClientOptions getClientOptions(final int reconnectAttempts) {
+        return new ProtonClientOptions().setConnectTimeout(DEFAULT_CONNECT_TIMEOUT_MILLIS)
+                .setReconnectAttempts(reconnectAttempts);
+    }
+
+    /**
+     * Closes the vert.x instance.
+     * 
+     * @return A future that will succeed once the instance is closed.
+     */
+    protected final Future<Void> closeVertx() {
+        final Future<Void> result = Future.future();
+        vertx.close(result.completer());
+        return result;
+    }
+}

jmeter/src/main/java/org/eclipse/hono/jmeter/client/HonoReceiver.java

@@ -174,7 +174,7 @@ private void noMessagesReceived(final SampleResult result) {
         result.setIdleTime(0);
     }
 
-    private void verifySenderTimeAndSetSamplingTime(final Long senderTime, long sampleReceivedTime) {
+    private void verifySenderTimeAndSetSamplingTime(final Long senderTime, final long sampleReceivedTime) {
         if (senderTime != null) {
             if (sampleStart == 0) { // set sample start only once when the first message is received.
                 sampleStart = senderTime;

legal/src/main/resources/checkstyle/default.xml

@@ -42,6 +42,7 @@
     <module name="HideUtilityClassConstructor"/>
     <module name="OneStatementPerLine" />
     <module name="StringLiteralEquality" />
+    <module name="FinalParameters"/>
 
     <!-- whitespaces, linebreaks -->
 

service-base/src/main/java/org/eclipse/hono/service/AbstractServiceBase.java

@@ -60,7 +60,7 @@ protected Future<Void> startInternal() {
      * @param stopFuture Will be completed if all of the invoked methods return a succeeded Future.
      */
     @Override
-    public final void stop(Future<Void> stopFuture) {
+    public final void stop(final Future<Void> stopFuture) {
         stopInternal().setHandler(stopFuture.completer());
     }
 

service-base/src/main/java/org/eclipse/hono/service/HealthCheckServer.java

@@ -63,7 +63,7 @@ public final class HealthCheckServer implements Lifecycle {
      * @throws NullPointerException if vertx is {@code null}.
      * @throws NullPointerException if config is {@code null}.
      */
-    public HealthCheckServer(Vertx vertx, ApplicationConfigProperties config) {
+    public HealthCheckServer(final Vertx vertx, final ApplicationConfigProperties config) {
         this.vertx = Objects.requireNonNull(vertx);
         this.config = Objects.requireNonNull(config);
 

service-base/src/main/java/org/eclipse/hono/service/amqp/AmqpServiceBase.java

@@ -731,7 +731,7 @@ public void registerReadinessChecks(final HealthCheckHandler handler) {
      * @param handler The health check handler to register the checks with.
      */
     @Override
-    public void registerLivenessChecks(HealthCheckHandler handler) {
+    public void registerLivenessChecks(final HealthCheckHandler handler) {
         for (AmqpEndpoint ep : endpoints()) {
             ep.registerLivenessChecks(handler);
         }

service-base/src/main/java/org/eclipse/hono/service/amqp/RequestResponseEndpoint.java

@@ -180,7 +180,7 @@ public final void onLinkAttach(final ProtonConnection con, final ProtonReceiver
      * @param message The message.
      */
     protected final void handleMessage(final ProtonConnection con, final ProtonReceiver receiver,
-            final ResourceIdentifier targetAddress, ProtonDelivery delivery, Message message) {
+            final ResourceIdentifier targetAddress, final ProtonDelivery delivery, final Message message) {
 
         final Future<Void> formalCheck = Future.future();
         if (passesFormalVerification(targetAddress, message)) {