Enable ModifierOrderCheck Checkstyle rule (#2673)

* Enable ModifierOrderCheck Checkstyle rule

* Fix violations for `static` and `abstract` modifier
* Remove redundant code in the `TcpNioConnection`
* Mark `connectionFactoryName` as `@Nullable` in the `TcpConnectionSupport`
ctor and its inheritors
* Fix some smells according IDEA suggestions in the affected classes
* This should fix some Sonar smells as well

* * Fix `HeaderMapperTests`

* * Polishing `TcpConnection` code style and fix Javdocs

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/DefaultTcpNioConnectionSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,12 +21,16 @@ import java.io.PushbackInputStream;
 import java.nio.channels.SocketChannel;
 
 import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.lang.Nullable;
 
 
 /**
  * Implementation of {@link TcpNioConnectionSupport} for non-SSL
  * NIO connections.
+ *
  * @author Gary Russell
+ * @author Artem Bilan
+ *
  * @since 2.2
  *
  */
@@ -56,8 +60,9 @@ public class DefaultTcpNioConnectionSupport extends AbstractTcpConnectionSupport
 		private volatile InputStream wrapped;
 
 		PushBackTcpNioConnection(SocketChannel socketChannel, boolean server, boolean lookupHost,
-				ApplicationEventPublisher applicationEventPublisher, String connectionFactoryName,
+				ApplicationEventPublisher applicationEventPublisher, @Nullable String connectionFactoryName,
 				int bufferSize) throws Exception {
+
 			super(socketChannel, server, lookupHost, applicationEventPublisher, connectionFactoryName);
 			this.pushbackBufferSize = bufferSize;
 			this.connectionId = "pushback:" + super.getConnectionId();

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpConnectionSupport.java

@@ -45,6 +45,8 @@ import org.springframework.util.Assert;
  * (incoming).
  *
  * @author Gary Russell
+ * @author Artem Bilan
+ *
  * @since 2.0
  *
  */
@@ -114,7 +116,8 @@ public abstract class TcpConnectionSupport implements TcpConnection {
 	 */
 	public TcpConnectionSupport(Socket socket, boolean server, boolean lookupHost,
 			ApplicationEventPublisher applicationEventPublisher,
-			String connectionFactoryName) {
+			@Nullable String connectionFactoryName) {
+
 		this.socketInfo = new SocketInfo(socket);
 		this.server = server;
 		InetAddress inetAddress = socket.getInetAddress();

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNioConnection.java

@@ -67,9 +67,13 @@ public class TcpNioConnection extends TcpConnectionSupport {
 
 	private final ChannelInputStream channelInputStream = new ChannelInputStream();
 
-	private volatile OutputStream bufferedOutputStream;
+	private final AtomicInteger executionControl = new AtomicInteger();
 
-	private volatile boolean usingDirectBuffers;
+	private boolean usingDirectBuffers;
+
+	private long pipeTimeout = DEFAULT_PIPE_TIMEOUT;
+
+	private volatile OutputStream bufferedOutputStream;
 
 	private volatile CompositeExecutor taskExecutor;
 
@@ -81,14 +85,10 @@ public class TcpNioConnection extends TcpConnectionSupport {
 
 	private volatile long lastSend;
 
-	private final AtomicInteger executionControl = new AtomicInteger();
-
 	private volatile boolean writingToPipe;
 
 	private volatile CountDownLatch writingLatch;
 
-	private volatile long pipeTimeout = DEFAULT_PIPE_TIMEOUT;
-
 	private volatile boolean timedOut;
 
 	/**
@@ -99,17 +99,13 @@ public class TcpNioConnection extends TcpConnectionSupport {
 	 * @param lookupHost true to perform reverse lookups.
 	 * @param applicationEventPublisher The event publisher.
 	 * @param connectionFactoryName The name of the connection factory creating this connection.
-	 * @throws Exception Any Exception.
 	 */
 	public TcpNioConnection(SocketChannel socketChannel, boolean server, boolean lookupHost,
 			ApplicationEventPublisher applicationEventPublisher,
-			String connectionFactoryName) throws Exception {
+			@Nullable String connectionFactoryName) {
+
 		super(socketChannel.socket(), server, lookupHost, applicationEventPublisher, connectionFactoryName);
 		this.socketChannel = socketChannel;
-		int receiveBufferSize = socketChannel.socket().getReceiveBufferSize();
-		if (receiveBufferSize <= 0) {
-			receiveBufferSize = this.maxMessageSize;
-		}
 		this.channelOutputStream = new ChannelOutputStream();
 	}
 
@@ -735,9 +731,8 @@ public class TcpNioConnection extends TcpConnectionSupport {
 
 		/**
 		 * Blocks if the blocking queue already contains 5 buffers.
-		 * @param array
-		 * @param bytesToWrite
-		 * @throws IOException
+		 * @param byteBuffer to write
+		 * @throws IOException writing to the buffer exception
 		 */
 		public void write(ByteBuffer byteBuffer) throws IOException {
 			int bytesToWrite = byteBuffer.limit() - byteBuffer.position();
@@ -774,7 +769,7 @@ public class TcpNioConnection extends TcpConnectionSupport {
 		}
 
 		@Override
-		public int available() throws IOException {
+		public int available() {
 			return this.available.get();
 		}
 

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNioSSLConnection.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,6 +31,7 @@ import javax.net.ssl.SSLHandshakeException;
 import javax.net.ssl.SSLSession;
 
 import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.MessagingException;
 import org.springframework.util.Assert;
 
@@ -48,7 +49,10 @@ import org.springframework.util.Assert;
  * Also, it may be deemed necessary to re-perform handshaking.<p>
  * This class supports the management of handshaking as necessary, both from the
  * initiating and receiving peers.
+ *
  * @author Gary Russell
+ * @author Artem Bilan
+ *
  * @since 2.2
  *
  */
@@ -77,8 +81,9 @@ public class TcpNioSSLConnection extends TcpNioConnection {
 	private SSLHandshakeException sslFatal;
 
 	public TcpNioSSLConnection(SocketChannel socketChannel, boolean server, boolean lookupHost,
-			ApplicationEventPublisher applicationEventPublisher, String connectionFactoryName,
+			ApplicationEventPublisher applicationEventPublisher, @Nullable String connectionFactoryName,
 			SSLEngine sslEngine) throws Exception {
+
 		super(socketChannel, server, lookupHost, applicationEventPublisher, connectionFactoryName);
 		this.sslEngine = sslEngine;
 	}

spring-integration-ip/src/test/java/org/springframework/integration/ip/tcp/connection/TcpNioConnectionTests.java

@@ -105,7 +105,7 @@ import org.springframework.util.StopWatch;
  */
 public class TcpNioConnectionTests {
 
-	private final static Log logger = LogFactory.getLog(TcpNioConnectionTests.class);
+	private static final Log logger = LogFactory.getLog(TcpNioConnectionTests.class);
 
 	@Rule
 	public Log4j2LevelAdjuster adjuster =
@@ -268,7 +268,7 @@ public class TcpNioConnectionTests {
 		connections.put(chan1, conn1);
 		connections.put(chan2, conn2);
 		connections.put(chan3, conn3);
-		final List<Field> fields = new ArrayList<Field>();
+		final List<Field> fields = new ArrayList<>();
 		ReflectionUtils.doWithFields(SocketChannel.class, field -> {
 			field.setAccessible(true);
 			fields.add(field);
@@ -279,7 +279,7 @@ public class TcpNioConnectionTests {
 		ReflectionUtils.setField(field, chan2, true);
 		ReflectionUtils.setField(field, chan3, true);
 		Selector selector = mock(Selector.class);
-		HashSet<SelectionKey> keys = new HashSet<SelectionKey>();
+		HashSet<SelectionKey> keys = new HashSet<>();
 		when(selector.selectedKeys()).thenReturn(keys);
 		factory.processNioSelections(1, selector, null, connections);
 		assertEquals(3, connections.size()); // all open