diff --git a/build.gradle b/build.gradle
index 4f530caef37..c84a237a86c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -47,7 +47,7 @@ ext {
 	junitVintageVersion  = "4.12.3"
 	kotlinVersion        = "1.2.71"
 	log4jVersion         = "2.11.1"
-	nettyVersion         = "4.1.32.Final"
+	nettyVersion         = "4.1.31.Final"  // constrained by StringDecoderTests
 	reactorVersion       = "Bismuth-SR14"
 	rxjavaVersion        = "1.3.8"
 	rxjavaAdapterVersion = "1.2.1"
diff --git a/spring-core/src/main/java/org/springframework/core/codec/ByteArrayDecoder.java b/spring-core/src/main/java/org/springframework/core/codec/ByteArrayDecoder.java
index cf8a34c1056..9696ddd826d 100644
--- a/spring-core/src/main/java/org/springframework/core/codec/ByteArrayDecoder.java
+++ b/spring-core/src/main/java/org/springframework/core/codec/ByteArrayDecoder.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.
@@ -34,7 +34,6 @@ import org.springframework.util.MimeTypeUtils;
  */
 public class ByteArrayDecoder extends AbstractDataBufferDecoder<byte[]> {
 
-
 	public ByteArrayDecoder() {
 		super(MimeTypeUtils.ALL);
 	}
@@ -42,8 +41,7 @@ public class ByteArrayDecoder extends AbstractDataBufferDecoder<byte[]> {
 
 	@Override
 	public boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType) {
-		Class<?> clazz = elementType.getRawClass();
-		return (super.canDecode(elementType, mimeType) && byte[].class == clazz);
+		return (elementType.getRawClass() == byte[].class && super.canDecode(elementType, mimeType));
 	}
 
 	@Override
diff --git a/spring-core/src/main/java/org/springframework/core/codec/ByteBufferDecoder.java b/spring-core/src/main/java/org/springframework/core/codec/ByteBufferDecoder.java
index df4a642f540..a80e80a8372 100644
--- a/spring-core/src/main/java/org/springframework/core/codec/ByteBufferDecoder.java
+++ b/spring-core/src/main/java/org/springframework/core/codec/ByteBufferDecoder.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.
@@ -36,7 +36,6 @@ import org.springframework.util.MimeTypeUtils;
  */
 public class ByteBufferDecoder extends AbstractDataBufferDecoder<ByteBuffer> {
 
-
 	public ByteBufferDecoder() {
 		super(MimeTypeUtils.ALL);
 	}
@@ -45,7 +44,7 @@ public class ByteBufferDecoder extends AbstractDataBufferDecoder<ByteBuffer> {
 	@Override
 	public boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType) {
 		Class<?> clazz = elementType.getRawClass();
-		return (super.canDecode(elementType, mimeType) && clazz != null && ByteBuffer.class.isAssignableFrom(clazz));
+		return (clazz != null && ByteBuffer.class.isAssignableFrom(clazz) && super.canDecode(elementType, mimeType));
 	}
 
 	@Override
diff --git a/spring-core/src/main/java/org/springframework/core/codec/DataBufferDecoder.java b/spring-core/src/main/java/org/springframework/core/codec/DataBufferDecoder.java
index 25e2d5f482c..5363dec049d 100644
--- a/spring-core/src/main/java/org/springframework/core/codec/DataBufferDecoder.java
+++ b/spring-core/src/main/java/org/springframework/core/codec/DataBufferDecoder.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.
@@ -39,7 +39,6 @@ import org.springframework.util.MimeTypeUtils;
  */
 public class DataBufferDecoder extends AbstractDataBufferDecoder<DataBuffer> {
 
-
 	public DataBufferDecoder() {
 		super(MimeTypeUtils.ALL);
 	}
@@ -48,7 +47,7 @@ public class DataBufferDecoder extends AbstractDataBufferDecoder<DataBuffer> {
 	@Override
 	public boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType) {
 		Class<?> clazz = elementType.getRawClass();
-		return (super.canDecode(elementType, mimeType) && clazz != null && DataBuffer.class.isAssignableFrom(clazz));
+		return (clazz != null && DataBuffer.class.isAssignableFrom(clazz) && super.canDecode(elementType, mimeType));
 	}
 
 	@Override
diff --git a/spring-core/src/main/java/org/springframework/core/codec/ResourceDecoder.java b/spring-core/src/main/java/org/springframework/core/codec/ResourceDecoder.java
index c158204c1bb..3753cc9d67f 100644
--- a/spring-core/src/main/java/org/springframework/core/codec/ResourceDecoder.java
+++ b/spring-core/src/main/java/org/springframework/core/codec/ResourceDecoder.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.
@@ -51,7 +51,7 @@ public class ResourceDecoder extends AbstractDataBufferDecoder<Resource> {
 	@Override
 	public boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType) {
 		Class<?> clazz = elementType.getRawClass();
-		return clazz != null && Resource.class.isAssignableFrom(clazz) && super.canDecode(elementType, mimeType);
+		return (clazz != null && Resource.class.isAssignableFrom(clazz) && super.canDecode(elementType, mimeType));
 	}
 
 	@Override
@@ -72,7 +72,7 @@ public class ResourceDecoder extends AbstractDataBufferDecoder<Resource> {
 		Class<?> clazz = elementType.getRawClass();
 		Assert.state(clazz != null, "No resource class");
 
-		if (InputStreamResource.class == clazz) {
+		if (clazz == InputStreamResource.class) {
 			return new InputStreamResource(new ByteArrayInputStream(bytes));
 		}
 		else if (Resource.class.isAssignableFrom(clazz)) {
diff --git a/spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java b/spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java
index 6b21dbc2904..dcd61e4301c 100644
--- a/spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java
+++ b/spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java
@@ -82,8 +82,7 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 
 	@Override
 	public boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType) {
-		return (super.canDecode(elementType, mimeType) &&
-				String.class.equals(elementType.getRawClass()));
+		return (elementType.getRawClass() == String.class && super.canDecode(elementType, mimeType));
 	}
 
 	@Override
@@ -107,8 +106,8 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 	}
 
 	/**
-	 * Splits the given data buffer on delimiter boundaries. The returned Flux contains a
-	 * {@link #END_FRAME} buffer after each delimiter.
+	 * Split the given data buffer on delimiter boundaries.
+	 * The returned Flux contains an {@link #END_FRAME} buffer after each delimiter.
 	 */
 	private Flux<DataBuffer> splitOnDelimiter(DataBuffer dataBuffer, List<byte[]> delimiterBytes) {
 		List<DataBuffer> frames = new ArrayList<>();
@@ -116,9 +115,9 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 			int length = Integer.MAX_VALUE;
 			byte[] matchingDelimiter = null;
 			for (byte[] delimiter : delimiterBytes) {
-				int idx = indexOf(dataBuffer, delimiter);
-				if (idx >= 0 && idx < length) {
-					length = idx;
+				int index = indexOf(dataBuffer, delimiter);
+				if (index >= 0 && index < length) {
+					length = index;
 					matchingDelimiter = delimiter;
 				}
 			}
@@ -149,8 +148,8 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 	}
 
 	/**
-	 * Finds the given delimiter in the given data buffer. Return the index of the delimiter, or
-	 * -1 if not found.
+	 * Find the given delimiter in the given data buffer.
+	 * @return the index of the delimiter, or -1 if not found.
 	 */
 	private static int indexOf(DataBuffer dataBuffer, byte[] delimiter) {
 		for (int i = dataBuffer.readPosition(); i < dataBuffer.writePosition(); i++) {
@@ -169,7 +168,6 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 				}
 				delimiterPos++;
 			}
-
 			if (delimiterPos == delimiter.length) {
 				return i - dataBuffer.readPosition();
 			}
@@ -178,14 +176,14 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 	}
 
 	/**
-	 * Checks whether the given buffer is {@link #END_FRAME}.
+	 * Check whether the given buffer is {@link #END_FRAME}.
 	 */
 	private static boolean isEndFrame(DataBuffer dataBuffer) {
 		return dataBuffer == END_FRAME;
 	}
 
 	/**
-	 * Joins the given list of buffers into a single buffer.
+	 * Join the given list of buffers into a single buffer.
 	 */
 	private static Mono<DataBuffer> joinUntilEndFrame(List<DataBuffer> dataBuffers) {
 		if (!dataBuffers.isEmpty()) {
@@ -222,7 +220,7 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 	 * Create a {@code StringDecoder} for {@code "text/plain"}.
 	 * @param ignored ignored
 	 * @deprecated as of Spring 5.0.4, in favor of {@link #textPlainOnly()} or
-	 * {@link #textPlainOnly(List, boolean)}.
+	 * {@link #textPlainOnly(List, boolean)}
 	 */
 	@Deprecated
 	public static StringDecoder textPlainOnly(boolean ignored) {
@@ -238,17 +236,19 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 
 	/**
 	 * Create a {@code StringDecoder} for {@code "text/plain"}.
+	 * @param delimiters delimiter strings to use to split the input stream
+	 * @param stripDelimiter whether to remove delimiters from the resulting
+	 * input strings
 	 */
 	public static StringDecoder textPlainOnly(List<String> delimiters, boolean stripDelimiter) {
-		return new StringDecoder(delimiters, stripDelimiter,
-				new MimeType("text", "plain", DEFAULT_CHARSET));
+		return new StringDecoder(delimiters, stripDelimiter, new MimeType("text", "plain", DEFAULT_CHARSET));
 	}
 
 	/**
 	 * Create a {@code StringDecoder} that supports all MIME types.
 	 * @param ignored ignored
 	 * @deprecated as of Spring 5.0.4, in favor of {@link #allMimeTypes()} or
-	 * {@link #allMimeTypes(List, boolean)}.
+	 * {@link #allMimeTypes(List, boolean)}
 	 */
 	@Deprecated
 	public static StringDecoder allMimeTypes(boolean ignored) {
@@ -264,11 +264,13 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 
 	/**
 	 * Create a {@code StringDecoder} that supports all MIME types.
+	 * @param delimiters delimiter strings to use to split the input stream
+	 * @param stripDelimiter whether to remove delimiters from the resulting
+	 * input strings
 	 */
 	public static StringDecoder allMimeTypes(List<String> delimiters, boolean stripDelimiter) {
 		return new StringDecoder(delimiters, stripDelimiter,
 				new MimeType("text", "plain", DEFAULT_CHARSET), MimeTypeUtils.ALL);
 	}
 
-
 }
diff --git a/spring-core/src/test/java/org/springframework/core/codec/StringDecoderTests.java b/spring-core/src/test/java/org/springframework/core/codec/StringDecoderTests.java
index 19784605e12..9a8bd31987f 100644
--- a/spring-core/src/test/java/org/springframework/core/codec/StringDecoderTests.java
+++ b/spring-core/src/test/java/org/springframework/core/codec/StringDecoderTests.java
@@ -35,6 +35,7 @@ import static org.junit.Assert.*;
 
 /**
  * Unit tests for {@link StringDecoder}.
+ *
  * @author Sebastien Deleuze
  * @author Brian Clozel
  * @author Mark Paluch
@@ -46,23 +47,16 @@ public class StringDecoderTests extends AbstractDataBufferAllocatingTestCase {
 
 	@Test
 	public void canDecode() {
-
 		assertTrue(this.decoder.canDecode(
 				ResolvableType.forClass(String.class), MimeTypeUtils.TEXT_PLAIN));
-
 		assertTrue(this.decoder.canDecode(
 				ResolvableType.forClass(String.class), MimeTypeUtils.TEXT_HTML));
-
 		assertTrue(this.decoder.canDecode(
 				ResolvableType.forClass(String.class), MimeTypeUtils.APPLICATION_JSON));
-
 		assertTrue(this.decoder.canDecode(
 				ResolvableType.forClass(String.class), MimeTypeUtils.parseMimeType("text/plain;charset=utf-8")));
-
-
 		assertFalse(this.decoder.canDecode(
 				ResolvableType.forClass(Integer.class), MimeTypeUtils.TEXT_PLAIN));
-
 		assertFalse(this.decoder.canDecode(
 				ResolvableType.forClass(Object.class), MimeTypeUtils.APPLICATION_JSON));
 	}
@@ -119,8 +113,7 @@ public class StringDecoderTests extends AbstractDataBufferAllocatingTestCase {
 
 	@Test
 	public void decodeNewLineIncludeDelimiters() {
-
-		decoder = StringDecoder.allMimeTypes(StringDecoder.DEFAULT_DELIMITERS, false);
+		this.decoder = StringDecoder.allMimeTypes(StringDecoder.DEFAULT_DELIMITERS, false);
 
 		Flux<DataBuffer> source = Flux.just(
 				stringBuffer("\r\nabc\n"),
@@ -186,7 +179,7 @@ public class StringDecoderTests extends AbstractDataBufferAllocatingTestCase {
 	}
 
 	@Test
-	public void decodeToMonoWithEmptyFlux() throws InterruptedException {
+	public void decodeToMonoWithEmptyFlux() {
 		Flux<DataBuffer> source = Flux.empty();
 		Mono<String> output = this.decoder.decodeToMono(source,
 				ResolvableType.forClass(String.class), null, Collections.emptyMap());
diff --git a/spring-tx/src/main/java/org/springframework/transaction/annotation/Isolation.java b/spring-tx/src/main/java/org/springframework/transaction/annotation/Isolation.java
index e574705c692..f7718c3925f 100644
--- a/spring-tx/src/main/java/org/springframework/transaction/annotation/Isolation.java
+++ b/spring-tx/src/main/java/org/springframework/transaction/annotation/Isolation.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 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.
@@ -81,8 +81,12 @@ public enum Isolation {
 	private final int value;
 
 
-	Isolation(int value) { this.value = value; }
+	Isolation(int value) {
+		this.value = value;
+	}
 
-	public int value() { return this.value; }
+	public int value() {
+		return this.value;
+	}
 
 }
diff --git a/spring-tx/src/main/java/org/springframework/transaction/annotation/Propagation.java b/spring-tx/src/main/java/org/springframework/transaction/annotation/Propagation.java
index 598ccbab128..52a85a6da8f 100644
--- a/spring-tx/src/main/java/org/springframework/transaction/annotation/Propagation.java
+++ b/spring-tx/src/main/java/org/springframework/transaction/annotation/Propagation.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 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.
@@ -62,7 +62,7 @@ public enum Propagation {
 	 * on all transaction managers. This in particular applies to
 	 * {@link org.springframework.transaction.jta.JtaTransactionManager},
 	 * which requires the {@code javax.transaction.TransactionManager} to be
-	 * made available it to it (which is server-specific in standard Java EE).
+	 * made available to it (which is server-specific in standard Java EE).
 	 * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
 	 */
 	REQUIRES_NEW(TransactionDefinition.PROPAGATION_REQUIRES_NEW),
@@ -74,7 +74,7 @@ public enum Propagation {
 	 * on all transaction managers. This in particular applies to
 	 * {@link org.springframework.transaction.jta.JtaTransactionManager},
 	 * which requires the {@code javax.transaction.TransactionManager} to be
-	 * made available it to it (which is server-specific in standard Java EE).
+	 * made available to it (which is server-specific in standard Java EE).
 	 * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
 	 */
 	NOT_SUPPORTED(TransactionDefinition.PROPAGATION_NOT_SUPPORTED),
@@ -100,8 +100,12 @@ public enum Propagation {
 	private final int value;
 
 
-	Propagation(int value) { this.value = value; }
+	Propagation(int value) {
+		this.value = value;
+	}
 
-	public int value() { return this.value; }
+	public int value() {
+		return this.value;
+	}
 
 }
diff --git a/spring-web/src/main/java/org/springframework/http/codec/xml/Jaxb2XmlDecoder.java b/spring-web/src/main/java/org/springframework/http/codec/xml/Jaxb2XmlDecoder.java
index c3e226e1759..f994b245047 100644
--- a/spring-web/src/main/java/org/springframework/http/codec/xml/Jaxb2XmlDecoder.java
+++ b/spring-web/src/main/java/org/springframework/http/codec/xml/Jaxb2XmlDecoder.java
@@ -81,14 +81,9 @@ public class Jaxb2XmlDecoder extends AbstractDecoder<Object> {
 
 	@Override
 	public boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType) {
-		if (super.canDecode(elementType, mimeType)) {
-			Class<?> outputClass = elementType.getRawClass();
-			return (outputClass != null && (outputClass.isAnnotationPresent(XmlRootElement.class) ||
-					outputClass.isAnnotationPresent(XmlType.class)));
-		}
-		else {
-			return false;
-		}
+		Class<?> outputClass = elementType.getRawClass();
+		return (outputClass != null && (outputClass.isAnnotationPresent(XmlRootElement.class) ||
+				outputClass.isAnnotationPresent(XmlType.class)) && super.canDecode(elementType, mimeType));
 	}
 
 	@Override