Nullability fine-tuning around bean properties

Issue: SPR-15720
Issue: SPR-15792

spring-beans/src/main/java/org/springframework/beans/factory/config/FieldRetrievingFactoryBean.java

@@ -126,7 +126,7 @@ public class FieldRetrievingFactoryBean
 	 * @see #setTargetObject
 	 */
 	public void setTargetField(@Nullable String targetField) {
-		this.targetField = StringUtils.trimAllWhitespace(targetField);
+		this.targetField = (targetField != null ? StringUtils.trimAllWhitespace(targetField) : null);
 	}
 
 	/**

spring-context/src/main/java/org/springframework/cache/interceptor/CacheAspectSupport.java

@@ -81,8 +81,7 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
-	private final Map<CacheOperationCacheKey, CacheOperationMetadata> metadataCache =
-			new ConcurrentHashMap<>(1024);
+	private final Map<CacheOperationCacheKey, CacheOperationMetadata> metadataCache = new ConcurrentHashMap<>(1024);
 
 	private final CacheOperationExpressionEvaluator evaluator = new CacheOperationExpressionEvaluator();
 
@@ -186,6 +185,7 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 	public void afterSingletonsInstantiated() {
 		if (getCacheResolver() == null) {
 			// Lazily initialize cache resolver via default cache manager...
+			Assert.state(this.beanFactory != null, "CacheResolver or BeanFactory must be set on cache aspect");
 			try {
 				setCacheManager(this.beanFactory.getBean(CacheManager.class));
 			}
@@ -289,6 +289,10 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 	 * @see CacheOperation#cacheResolver
 	 */
 	protected <T> T getBean(String beanName, Class<T> expectedType) {
+		if (this.beanFactory == null) {
+			throw new IllegalStateException(
+					"BeanFactory must be set on cache aspect for " + expectedType.getSimpleName() + " retrieval");
+		}
 		return BeanFactoryAnnotationUtils.qualifiedBeanOfType(this.beanFactory, expectedType, beanName);
 	}
 

spring-context/src/main/java/org/springframework/context/support/AbstractResourceBasedMessageSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -38,6 +38,7 @@ public abstract class AbstractResourceBasedMessageSource extends AbstractMessage
 
 	private final Set<String> basenameSet = new LinkedHashSet<>(4);
 
+	@Nullable
 	private String defaultEncoding;
 
 	private boolean fallbackToSystemLocale = true;

spring-context/src/main/java/org/springframework/validation/DataBinder.java

@@ -535,9 +535,6 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 	}
 
 	private void assertValidators(Validator... validators) {
-		if (validators == null) {
-			return;
-		}
 		for (Validator validator : validators) {
 			if (validator != null && (getTarget() != null && !validator.supports(getTarget().getClass()))) {
 				throw new IllegalStateException("Invalid target for Validator [" + validator + "]: " + getTarget());

spring-core/src/main/java/org/springframework/util/CustomizableThreadCreator.java

@@ -41,6 +41,7 @@ public class CustomizableThreadCreator implements Serializable {
 
 	private boolean daemon = false;
 
+	@Nullable
 	private ThreadGroup threadGroup;
 
 	private final AtomicInteger threadCount = new AtomicInteger(0);

spring-core/src/main/java/org/springframework/util/concurrent/ListenableFutureCallbackRegistry.java

@@ -132,7 +132,7 @@ public class ListenableFutureCallbackRegistry<T> {
 	 * added callbacks with the given result.
 	 * @param result the result to trigger the callbacks with
 	 */
-	public void success(T result) {
+	public void success(@Nullable T result) {
 		synchronized (this.mutex) {
 			this.state = State.SUCCESS;
 			this.result = result;

spring-core/src/main/java/org/springframework/util/xml/AbstractXMLReader.java

@@ -144,6 +144,7 @@ abstract class AbstractXMLReader implements XMLReader {
 	 * handler. The property name for a lexical handler is {@code http://xml.org/sax/properties/lexical-handler}.
 	 */
 	@Override
+	@Nullable
 	public Object getProperty(String name) throws SAXNotRecognizedException, SAXNotSupportedException {
 		if ("http://xml.org/sax/properties/lexical-handler".equals(name)) {
 			return this.lexicalHandler;

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/CallMetaDataContext.java

@@ -244,6 +244,19 @@ public class CallMetaDataContext {
 	}
 
 
+	/**
+	 * Initialize this class with metadata from the database.
+	 * @param dataSource the DataSource used to retrieve metadata
+	 */
+	public void initializeMetaData(DataSource dataSource) {
+		this.metaDataProvider = CallMetaDataProviderFactory.createMetaDataProvider(dataSource, this);
+	}
+
+	private CallMetaDataProvider obtainMetaDataProvider() {
+		Assert.state(this.metaDataProvider != null, "No CallMetaDataProvider - call initializeMetaData first");
+		return this.metaDataProvider;
+	}
+
 	/**
 	 * Create a ReturnResultSetParameter/SqlOutParameter depending on the support provided
 	 * by the JDBC driver used for the database in use.
@@ -252,13 +265,13 @@ public class CallMetaDataContext {
 	 * @return the appropriate SqlParameter
 	 */
 	public SqlParameter createReturnResultSetParameter(String parameterName, RowMapper<?> rowMapper) {
-		Assert.state(this.metaDataProvider != null, "No CallMetaDataProvider available");
-		if (this.metaDataProvider.isReturnResultSetSupported()) {
+		CallMetaDataProvider provider = obtainMetaDataProvider();
+		if (provider.isReturnResultSetSupported()) {
 			return new SqlReturnResultSet(parameterName, rowMapper);
 		}
 		else {
-			if (this.metaDataProvider.isRefCursorSupported()) {
-				return new SqlOutParameter(parameterName, this.metaDataProvider.getRefCursorSqlType(), rowMapper);
+			if (provider.isRefCursorSupported()) {
+				return new SqlOutParameter(parameterName, provider.getRefCursorSqlType(), rowMapper);
 			}
 			else {
 				throw new InvalidDataAccessApiUsageException("Return of a ResultSet from a stored procedure is not supported.");
@@ -290,14 +303,6 @@ public class CallMetaDataContext {
 		return this.callParameters;
 	}
 
-	/**
-	 * Initialize this class with metadata from the database.
-	 * @param dataSource the DataSource used to retrieve metadata
-	 */
-	public void initializeMetaData(DataSource dataSource) {
-		this.metaDataProvider = CallMetaDataProviderFactory.createMetaDataProvider(dataSource, this);
-	}
-
 	/**
 	 * Process the list of parameters provided, and if procedure column metadata is used,
 	 * the parameters will be matched against the metadata information and any missing
@@ -312,7 +317,7 @@ public class CallMetaDataContext {
 	 * Reconcile the provided parameters with available metadata and add new ones where appropriate.
 	 */
 	protected List<SqlParameter> reconcileParameters(List<SqlParameter> parameters) {
-		Assert.state(this.metaDataProvider != null, "No CallMetaDataProvider available");
+		CallMetaDataProvider provider = obtainMetaDataProvider();
 
 		final List<SqlParameter> declaredReturnParams = new ArrayList<>();
 		final Map<String, SqlParameter> declaredParams = new LinkedHashMap<>();
@@ -321,7 +326,7 @@ public class CallMetaDataContext {
 		List<String> metaDataParamNames = new ArrayList<>();
 
 		// Get the names of the meta data parameters
-		for (CallParameterMetaData meta : this.metaDataProvider.getCallParameterMetaData()) {
+		for (CallParameterMetaData meta : provider.getCallParameterMetaData()) {
 			if (meta.getParameterType() != DatabaseMetaData.procedureColumnReturn) {
 				metaDataParamNames.add(lowerCase(meta.getParameterName()));
 			}
@@ -338,7 +343,7 @@ public class CallMetaDataContext {
 					throw new IllegalArgumentException("Anonymous parameters not supported for calls - " +
 							"please specify a name for the parameter of SQL type " + param.getSqlType());
 				}
-				String paramNameToMatch = lowerCase(this.metaDataProvider.parameterNameToUse(paramName));
+				String paramNameToMatch = lowerCase(provider.parameterNameToUse(paramName));
 				declaredParams.put(paramNameToMatch, param);
 				if (param instanceof SqlOutParameter) {
 					outParamNames.add(paramName);
@@ -360,24 +365,23 @@ public class CallMetaDataContext {
 		List<SqlParameter> workParams = new ArrayList<>();
 		workParams.addAll(declaredReturnParams);
 
-		if (!this.metaDataProvider.isProcedureColumnMetaDataUsed()) {
+		if (!provider.isProcedureColumnMetaDataUsed()) {
 			workParams.addAll(declaredParams.values());
 			return workParams;
 		}
 
 		Map<String, String> limitedInParamNamesMap = new HashMap<>(this.limitedInParameterNames.size());
 		for (String limitedParamName : this.limitedInParameterNames) {
-			limitedInParamNamesMap.put(
-					lowerCase(this.metaDataProvider.parameterNameToUse(limitedParamName)), limitedParamName);
+			limitedInParamNamesMap.put(lowerCase(provider.parameterNameToUse(limitedParamName)), limitedParamName);
 		}
 
-		for (CallParameterMetaData meta : this.metaDataProvider.getCallParameterMetaData()) {
+		for (CallParameterMetaData meta : provider.getCallParameterMetaData()) {
 			String paramName = meta.getParameterName();
 			String paramNameToCheck = null;
 			if (paramName != null) {
-				paramNameToCheck = lowerCase(this.metaDataProvider.parameterNameToUse(paramName));
+				paramNameToCheck = lowerCase(provider.parameterNameToUse(paramName));
 			}
-			String paramNameToUse = this.metaDataProvider.parameterNameToUse(paramName);
+			String paramNameToUse = provider.parameterNameToUse(paramName);
 			if (declaredParams.containsKey(paramNameToCheck) ||
 					(meta.getParameterType() == DatabaseMetaData.procedureColumnReturn && returnDeclared)) {
 				SqlParameter param;
@@ -409,7 +413,7 @@ public class CallMetaDataContext {
 			else {
 				if (meta.getParameterType() == DatabaseMetaData.procedureColumnReturn) {
 					if (!isFunction() && !isReturnValueRequired() && paramName != null &&
-							this.metaDataProvider.byPassReturnParameter(paramName)) {
+							provider.byPassReturnParameter(paramName)) {
 						if (logger.isDebugEnabled()) {
 							logger.debug("Bypassing metadata return parameter for '" + paramName + "'");
 						}
@@ -417,7 +421,7 @@ public class CallMetaDataContext {
 					else {
 						String returnNameToUse =
 								(StringUtils.hasLength(paramNameToUse) ? paramNameToUse : getFunctionReturnName());
-						workParams.add(this.metaDataProvider.createDefaultOutParameter(returnNameToUse, meta));
+						workParams.add(provider.createDefaultOutParameter(returnNameToUse, meta));
 						if (isFunction()) {
 							setFunctionReturnName(returnNameToUse);
 							outParamNames.add(returnNameToUse);
@@ -432,14 +436,14 @@ public class CallMetaDataContext {
 						paramNameToUse = "";
 					}
 					if (meta.getParameterType() == DatabaseMetaData.procedureColumnOut) {
-						workParams.add(this.metaDataProvider.createDefaultOutParameter(paramNameToUse, meta));
+						workParams.add(provider.createDefaultOutParameter(paramNameToUse, meta));
 						outParamNames.add(paramNameToUse);
 						if (logger.isDebugEnabled()) {
 							logger.debug("Added metadata out parameter for '" + paramNameToUse + "'");
 						}
 					}
 					else if (meta.getParameterType() == DatabaseMetaData.procedureColumnInOut) {
-						workParams.add(this.metaDataProvider.createDefaultInOutParameter(paramNameToUse, meta));
+						workParams.add(provider.createDefaultInOutParameter(paramNameToUse, meta));
 						outParamNames.add(paramNameToUse);
 						if (logger.isDebugEnabled()) {
 							logger.debug("Added metadata in out parameter for '" + paramNameToUse + "'");
@@ -448,7 +452,7 @@ public class CallMetaDataContext {
 					else {
 						if (this.limitedInParameterNames.isEmpty() ||
 								limitedInParamNamesMap.containsKey(lowerCase(paramNameToUse))) {
-							workParams.add(this.metaDataProvider.createDefaultInParameter(paramNameToUse, meta));
+							workParams.add(provider.createDefaultInParameter(paramNameToUse, meta));
 							if (logger.isDebugEnabled()) {
 								logger.debug("Added metadata in parameter for '" + paramNameToUse + "'");
 							}
@@ -473,8 +477,6 @@ public class CallMetaDataContext {
 	 * @return a Map containing the matched parameter names with the value taken from the input
 	 */
 	public Map<String, Object> matchInParameterValuesWithCallParameters(SqlParameterSource parameterSource) {
-		Assert.state(this.metaDataProvider != null, "No CallMetaDataProvider available");
-
 		// For parameter source lookups we need to provide case-insensitive lookup support
 		// since the database metadata is not necessarily providing case sensitive parameter names.
 		Map<String, String> caseInsensitiveParameterNames =
@@ -485,7 +487,7 @@ public class CallMetaDataContext {
 		for (SqlParameter parameter : this.callParameters) {
 			if (parameter.isInputValueProvided()) {
 				String parameterName = parameter.getName();
-				String parameterNameToMatch = this.metaDataProvider.parameterNameToUse(parameterName);
+				String parameterNameToMatch = obtainMetaDataProvider().parameterNameToUse(parameterName);
 				if (parameterNameToMatch != null) {
 					callParameterNames.put(parameterNameToMatch.toLowerCase(), parameterName);
 				}
@@ -538,8 +540,8 @@ public class CallMetaDataContext {
 	 * @return a Map containing the matched parameter names with the value taken from the input
 	 */
 	public Map<String, ?> matchInParameterValuesWithCallParameters(Map<String, ?> inParameters) {
-		Assert.state(this.metaDataProvider != null, "No CallMetaDataProvider available");
-		if (!this.metaDataProvider.isProcedureColumnMetaDataUsed()) {
+		CallMetaDataProvider provider = obtainMetaDataProvider();
+		if (!provider.isProcedureColumnMetaDataUsed()) {
 			return inParameters;
 		}
 
@@ -547,7 +549,7 @@ public class CallMetaDataContext {
 		for (SqlParameter parameter : this.callParameters) {
 			if (parameter.isInputValueProvided()) {
 				String parameterName =  parameter.getName();
-				String parameterNameToMatch = this.metaDataProvider.parameterNameToUse(parameterName);
+				String parameterNameToMatch = provider.parameterNameToUse(parameterName);
 				if (parameterNameToMatch != null) {
 					callParameterNames.put(parameterNameToMatch.toLowerCase(), parameterName);
 				}
@@ -556,7 +558,7 @@ public class CallMetaDataContext {
 
 		Map<String, Object> matchedParameters = new HashMap<>(inParameters.size());
 		for (String parameterName : inParameters.keySet()) {
-			String parameterNameToMatch = this.metaDataProvider.parameterNameToUse(parameterName);
+			String parameterNameToMatch = provider.parameterNameToUse(parameterName);
 			String callParameterName = callParameterNames.get(lowerCase(parameterNameToMatch));
 			if (callParameterName == null) {
 				if (logger.isDebugEnabled()) {
@@ -577,7 +579,7 @@ public class CallMetaDataContext {
 
 		if (matchedParameters.size() < callParameterNames.size()) {
 			for (String parameterName : callParameterNames.keySet()) {
-				String parameterNameToMatch = this.metaDataProvider.parameterNameToUse(parameterName);
+				String parameterNameToMatch = provider.parameterNameToUse(parameterName);
 				String callParameterName = callParameterNames.get(lowerCase(parameterNameToMatch));
 				if (!matchedParameters.containsKey(callParameterName)) {
 					logger.warn("Unable to locate the corresponding parameter value for '" + parameterName +

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/TableMetaDataContext.java

@@ -33,6 +33,7 @@ import org.springframework.jdbc.core.namedparam.SqlParameterSource;
 import org.springframework.jdbc.core.namedparam.SqlParameterSourceUtils;
 import org.springframework.jdbc.support.JdbcUtils;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Class to manage context metadata used for the configuration
@@ -47,13 +48,16 @@ public class TableMetaDataContext {
 	/** Logger available to subclasses */
 	protected final Log logger = LogFactory.getLog(getClass());
 
-	/** name of table for this context **/
+	/** Name of table for this context */
+	@Nullable
 	private String tableName;
 
-	/** name of catalog for this context **/
+	/** Name of catalog for this context */
+	@Nullable
 	private String catalogName;
 
-	/** name of schema for this context **/
+	/** Name of schema for this context */
+	@Nullable
 	private String schemaName;
 
 	/** List of columns objects to be used in this context */
@@ -66,6 +70,7 @@ public class TableMetaDataContext {
 	private boolean overrideIncludeSynonymsDefault = false;
 
 	/** the provider of table meta data */
+	@Nullable
 	private TableMetaDataProvider metaDataProvider;
 
 	/** are we using generated key columns */
@@ -153,41 +158,6 @@ public class TableMetaDataContext {
 		return this.tableColumns;
 	}
 
-	/**
-	 * Does this database support the JDBC 3.0 feature of retrieving generated keys
-	 * {@link java.sql.DatabaseMetaData#supportsGetGeneratedKeys()}?
-	 */
-	public boolean isGetGeneratedKeysSupported() {
-		return this.metaDataProvider.isGetGeneratedKeysSupported();
-	}
-
-	/**
-	 * Does this database support simple query to retrieve generated keys
-	 * when the JDBC 3.0 feature is not supported.
-	 * {@link java.sql.DatabaseMetaData#supportsGetGeneratedKeys()}?
-	 */
-	public boolean isGetGeneratedKeysSimulated() {
-		return this.metaDataProvider.isGetGeneratedKeysSimulated();
-	}
-
-	/**
-	 * Does this database support simple query to retrieve generated keys
-	 * when the JDBC 3.0 feature is not supported.
-	 * {@link java.sql.DatabaseMetaData#supportsGetGeneratedKeys()}?
-	 */
-	@Nullable
-	public String getSimulationQueryForGetGeneratedKey(String tableName, String keyColumnName) {
-		return this.metaDataProvider.getSimpleQueryForGetGeneratedKey(tableName, keyColumnName);
-	}
-
-	/**
-	 * Is a column name String array for retrieving generated keys supported?
-	 * {@link java.sql.Connection#createStruct(String, Object[])}?
-	 */
-	public boolean isGeneratedKeysColumnNameArraySupported() {
-		return this.metaDataProvider.isGeneratedKeysColumnNameArraySupported();
-	}
-
 
 	/**
 	 * Process the current meta data with the provided configuration options.
@@ -200,6 +170,11 @@ public class TableMetaDataContext {
 		this.tableColumns = reconcileColumnsToUse(declaredColumns, generatedKeyNames);
 	}
 
+	private TableMetaDataProvider obtainMetaDataProvider() {
+		Assert.state(this.metaDataProvider != null, "No TableMetaDataProvider - call processMetaData first");
+		return this.metaDataProvider;
+	}
+
 	/**
 	 * Compare columns created from metadata with declared columns and return a reconciled list.
 	 * @param declaredColumns declared column names
@@ -217,7 +192,7 @@ public class TableMetaDataContext {
 			keys.add(key.toUpperCase());
 		}
 		List<String> columns = new ArrayList<>();
-		for (TableParameterMetaData meta : metaDataProvider.getTableParameterMetaData()) {
+		for (TableParameterMetaData meta : obtainMetaDataProvider().getTableParameterMetaData()) {
 			if (!keys.contains(meta.getParameterName().toUpperCase())) {
 				columns.add(meta.getParameterName());
 			}
@@ -336,7 +311,7 @@ public class TableMetaDataContext {
 	 */
 	public int[] createInsertTypes() {
 		int[] types = new int[getTableColumns().size()];
-		List<TableParameterMetaData> parameters = this.metaDataProvider.getTableParameterMetaData();
+		List<TableParameterMetaData> parameters = obtainMetaDataProvider().getTableParameterMetaData();
 		Map<String, TableParameterMetaData> parameterMap =
 				new LinkedHashMap<>(parameters.size());
 		for (TableParameterMetaData tpmd : parameters) {
@@ -361,4 +336,40 @@ public class TableMetaDataContext {
 		return types;
 	}
 
+
+	/**
+	 * Does this database support the JDBC 3.0 feature of retrieving generated keys
+	 * {@link java.sql.DatabaseMetaData#supportsGetGeneratedKeys()}?
+	 */
+	public boolean isGetGeneratedKeysSupported() {
+		return obtainMetaDataProvider().isGetGeneratedKeysSupported();
+	}
+
+	/**
+	 * Does this database support simple query to retrieve generated keys
+	 * when the JDBC 3.0 feature is not supported.
+	 * {@link java.sql.DatabaseMetaData#supportsGetGeneratedKeys()}?
+	 */
+	public boolean isGetGeneratedKeysSimulated() {
+		return obtainMetaDataProvider().isGetGeneratedKeysSimulated();
+	}
+
+	/**
+	 * Does this database support simple query to retrieve generated keys
+	 * when the JDBC 3.0 feature is not supported.
+	 * {@link java.sql.DatabaseMetaData#supportsGetGeneratedKeys()}?
+	 */
+	@Nullable
+	public String getSimulationQueryForGetGeneratedKey(String tableName, String keyColumnName) {
+		return obtainMetaDataProvider().getSimpleQueryForGetGeneratedKey(tableName, keyColumnName);
+	}
+
+	/**
+	 * Is a column name String array for retrieving generated keys supported?
+	 * {@link java.sql.Connection#createStruct(String, Object[])}?
+	 */
+	public boolean isGeneratedKeysColumnNameArraySupported() {
+		return obtainMetaDataProvider().isGeneratedKeysColumnNameArraySupported();
+	}
+
 }

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/AbstractDriverBasedDataSource.java

@@ -21,7 +21,6 @@ import java.sql.SQLException;
 import java.util.Properties;
 
 import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
 
 /**
  * Abstract base class for JDBC {@link javax.sql.DataSource} implementations
@@ -58,8 +57,7 @@ public abstract class AbstractDriverBasedDataSource extends AbstractDataSource {
 	 * @see java.sql.Driver#connect(String, java.util.Properties)
 	 */
 	public void setUrl(@Nullable String url) {
-		Assert.hasText(url, "Property 'url' must not be empty");
-		this.url = url.trim();
+		this.url = (url != null ? url.trim() : null);
 	}
 
 	/**

spring-jdbc/src/main/java/org/springframework/jdbc/support/CustomSQLErrorCodesTranslation.java

@@ -33,6 +33,7 @@ public class CustomSQLErrorCodesTranslation {
 
 	private String[] errorCodes = new String[0];
 
+	@Nullable
 	private Class<?> exceptionClass;
 
 

spring-jms/src/main/java/org/springframework/jms/connection/TransactionAwareConnectionFactoryProxy.java

@@ -79,11 +79,11 @@ import org.springframework.util.Assert;
 public class TransactionAwareConnectionFactoryProxy
 		implements ConnectionFactory, QueueConnectionFactory, TopicConnectionFactory {
 
-	private boolean synchedLocalTransactionAllowed = false;
-
 	@Nullable
 	private ConnectionFactory targetConnectionFactory;
 
+	private boolean synchedLocalTransactionAllowed = false;
+
 
 	/**
 	 * Create a new TransactionAwareConnectionFactoryProxy.
@@ -103,16 +103,18 @@ public class TransactionAwareConnectionFactoryProxy
 	/**
 	 * Set the target ConnectionFactory that this ConnectionFactory should delegate to.
 	 */
-	public final void setTargetConnectionFactory(@Nullable ConnectionFactory targetConnectionFactory) {
+	public final void setTargetConnectionFactory(ConnectionFactory targetConnectionFactory) {
+		Assert.notNull(targetConnectionFactory, "'targetConnectionFactory' must not be null");
 		this.targetConnectionFactory = targetConnectionFactory;
 	}
 
 	/**
 	 * Return the target ConnectionFactory that this ConnectionFactory should delegate to.
 	 */
-	@Nullable
 	protected ConnectionFactory getTargetConnectionFactory() {
-		return this.targetConnectionFactory;
+		ConnectionFactory target = this.targetConnectionFactory;
+		Assert.state(target != null, "'targetConnectionFactory' is required");
+		return target;
 	}
 
 	/**
@@ -141,19 +143,19 @@ public class TransactionAwareConnectionFactoryProxy
 
 	@Override
 	public Connection createConnection() throws JMSException {
-		Connection targetConnection = this.targetConnectionFactory.createConnection();
+		Connection targetConnection = getTargetConnectionFactory().createConnection();
 		return getTransactionAwareConnectionProxy(targetConnection);
 	}
 
 	@Override
 	public Connection createConnection(String username, String password) throws JMSException {
-		Connection targetConnection = obtainTargetConnectionFactory().createConnection(username, password);
+		Connection targetConnection = getTargetConnectionFactory().createConnection(username, password);
 		return getTransactionAwareConnectionProxy(targetConnection);
 	}
 
 	@Override
 	public QueueConnection createQueueConnection() throws JMSException {
-		ConnectionFactory target = obtainTargetConnectionFactory();
+		ConnectionFactory target = getTargetConnectionFactory();
 		if (!(target instanceof QueueConnectionFactory)) {
 			throw new javax.jms.IllegalStateException("'targetConnectionFactory' is no QueueConnectionFactory");
 		}
@@ -163,7 +165,7 @@ public class TransactionAwareConnectionFactoryProxy
 
 	@Override
 	public QueueConnection createQueueConnection(String username, String password) throws JMSException {
-		ConnectionFactory target = obtainTargetConnectionFactory();
+		ConnectionFactory target = getTargetConnectionFactory();
 		if (!(target instanceof QueueConnectionFactory)) {
 			throw new javax.jms.IllegalStateException("'targetConnectionFactory' is no QueueConnectionFactory");
 		}
@@ -173,7 +175,7 @@ public class TransactionAwareConnectionFactoryProxy
 
 	@Override
 	public TopicConnection createTopicConnection() throws JMSException {
-		ConnectionFactory target = obtainTargetConnectionFactory();
+		ConnectionFactory target = getTargetConnectionFactory();
 		if (!(target instanceof TopicConnectionFactory)) {
 			throw new javax.jms.IllegalStateException("'targetConnectionFactory' is no TopicConnectionFactory");
 		}
@@ -183,7 +185,7 @@ public class TransactionAwareConnectionFactoryProxy
 
 	@Override
 	public TopicConnection createTopicConnection(String username, String password) throws JMSException {
-		ConnectionFactory target = obtainTargetConnectionFactory();
+		ConnectionFactory target = getTargetConnectionFactory();
 		if (!(target instanceof TopicConnectionFactory)) {
 			throw new javax.jms.IllegalStateException("'targetConnectionFactory' is no TopicConnectionFactory");
 		}
@@ -193,28 +195,22 @@ public class TransactionAwareConnectionFactoryProxy
 
 	@Override
 	public JMSContext createContext() {
-		return obtainTargetConnectionFactory().createContext();
+		return getTargetConnectionFactory().createContext();
 	}
 
 	@Override
 	public JMSContext createContext(String userName, String password) {
-		return obtainTargetConnectionFactory().createContext(userName, password);
+		return getTargetConnectionFactory().createContext(userName, password);
 	}
 
 	@Override
 	public JMSContext createContext(String userName, String password, int sessionMode) {
-		return obtainTargetConnectionFactory().createContext(userName, password, sessionMode);
+		return getTargetConnectionFactory().createContext(userName, password, sessionMode);
 	}
 
 	@Override
 	public JMSContext createContext(int sessionMode) {
-		return obtainTargetConnectionFactory().createContext(sessionMode);
-	}
-
-	private ConnectionFactory obtainTargetConnectionFactory() {
-		ConnectionFactory target = getTargetConnectionFactory();
-		Assert.state(target != null, "'targetConnectionFactory' is required");
-		return target;
+		return getTargetConnectionFactory().createContext(sessionMode);
 	}
 
 
@@ -265,14 +261,14 @@ public class TransactionAwareConnectionFactoryProxy
 			}
 			else if (Session.class == method.getReturnType()) {
 				Session session = ConnectionFactoryUtils.getTransactionalSession(
-						obtainTargetConnectionFactory(), this.target, isSynchedLocalTransactionAllowed());
+						getTargetConnectionFactory(), this.target, isSynchedLocalTransactionAllowed());
 				if (session != null) {
 					return getCloseSuppressingSessionProxy(session);
 				}
 			}
 			else if (QueueSession.class == method.getReturnType()) {
 				QueueSession session = ConnectionFactoryUtils.getTransactionalQueueSession(
-						(QueueConnectionFactory) obtainTargetConnectionFactory(), (QueueConnection) this.target,
+						(QueueConnectionFactory) getTargetConnectionFactory(), (QueueConnection) this.target,
 						isSynchedLocalTransactionAllowed());
 				if (session != null) {
 					return getCloseSuppressingSessionProxy(session);
@@ -280,7 +276,7 @@ public class TransactionAwareConnectionFactoryProxy
 			}
 			else if (TopicSession.class == method.getReturnType()) {
 				TopicSession session = ConnectionFactoryUtils.getTransactionalTopicSession(
-						(TopicConnectionFactory) obtainTargetConnectionFactory(), (TopicConnection) this.target,
+						(TopicConnectionFactory) getTargetConnectionFactory(), (TopicConnection) this.target,
 						isSynchedLocalTransactionAllowed());
 				if (session != null) {
 					return getCloseSuppressingSessionProxy(session);

spring-jms/src/main/java/org/springframework/jms/core/JmsTemplate.java

@@ -95,6 +95,7 @@ public class JmsTemplate extends JmsDestinationAccessor implements JmsOperations
 	@Nullable
 	private Object defaultDestination;
 
+	@Nullable
 	private MessageConverter messageConverter;
 
 
@@ -228,13 +229,14 @@ public class JmsTemplate extends JmsDestinationAccessor implements JmsOperations
 	 * @see #receiveAndConvert
 	 * @see org.springframework.jms.support.converter.SimpleMessageConverter
 	 */
-	public void setMessageConverter(MessageConverter messageConverter) {
+	public void setMessageConverter(@Nullable MessageConverter messageConverter) {
 		this.messageConverter = messageConverter;
 	}
 
 	/**
 	 * Return the message converter for this template.
 	 */
+	@Nullable
 	public MessageConverter getMessageConverter() {
 		return this.messageConverter;
 	}

spring-jms/src/main/java/org/springframework/jms/listener/adapter/AbstractAdaptableMessageListener.java

@@ -65,6 +65,7 @@ public abstract class AbstractAdaptableMessageListener
 
 	private DestinationResolver destinationResolver = new DynamicDestinationResolver();
 
+	@Nullable
 	private MessageConverter messageConverter = new SimpleMessageConverter();
 
 	private final MessagingMessageConverterAdapter messagingMessageConverter = new MessagingMessageConverterAdapter();

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/AbstractMethodMessageHandler.java

@@ -232,11 +232,15 @@ public abstract class AbstractMethodMessageHandler<T>
 			this.returnValueHandlers.addHandlers(initReturnValueHandlers());
 		}
 
-		for (String beanName : this.applicationContext.getBeanNamesForType(Object.class)) {
+		ApplicationContext context = getApplicationContext();
+		if (context == null) {
+			return;
+		}
+		for (String beanName : context.getBeanNamesForType(Object.class)) {
 			if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) {
 				Class<?> beanType = null;
 				try {
-					beanType = this.applicationContext.getType(beanName);
+					beanType = context.getType(beanName);
 				}
 				catch (Throwable ex) {
 					// An unresolvable bean type, probably from a lazy bean - let's ignore it.
@@ -279,8 +283,15 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * @param handler the handler to check, either an instance of a Spring bean name
 	 */
 	protected final void detectHandlerMethods(final Object handler) {
-		Class<?> handlerType = (handler instanceof String ?
-				this.applicationContext.getType((String) handler) : handler.getClass());
+		Class<?> handlerType;
+		if (handler instanceof String) {
+			ApplicationContext context = getApplicationContext();
+			Assert.state(context != null, "ApplicationContext is required for resolving handler bean names");
+			handlerType = context.getType((String) handler);
+		}
+		else {
+			handlerType = handler.getClass();
+		}
 
 		if (handlerType != null) {
 			final Class<?> userType = ClassUtils.getUserClass(handlerType);
@@ -338,9 +349,10 @@ public abstract class AbstractMethodMessageHandler<T>
 	protected HandlerMethod createHandlerMethod(Object handler, Method method) {
 		HandlerMethod handlerMethod;
 		if (handler instanceof String) {
+			ApplicationContext context = getApplicationContext();
+			Assert.state(context != null, "ApplicationContext is required for resolving handler bean names");
 			String beanName = (String) handler;
-			handlerMethod = new HandlerMethod(beanName,
-					this.applicationContext.getAutowireCapableBeanFactory(), method);
+			handlerMethod = new HandlerMethod(beanName, context.getAutowireCapableBeanFactory(), method);
 		}
 		else {
 			handlerMethod = new HandlerMethod(handler, method);
@@ -645,7 +657,7 @@ public abstract class AbstractMethodMessageHandler<T>
 		}
 
 		@Override
-		public void onSuccess(Object result) {
+		public void onSuccess(@Nullable Object result) {
 			try {
 				MethodParameter returnType = this.handlerMethod.getAsyncReturnValueType(result);
 				returnValueHandlers.handleReturnValue(result, returnType, this.message);

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethod.java

@@ -252,7 +252,7 @@ public class InvocableHandlerMethod extends HandlerMethod {
 	}
 
 
-	MethodParameter getAsyncReturnValueType(Object returnValue) {
+	MethodParameter getAsyncReturnValueType(@Nullable Object returnValue) {
 		return new AsyncResultMethodParameter(returnValue);
 	}
 
@@ -264,7 +264,7 @@ public class InvocableHandlerMethod extends HandlerMethod {
 
 		private final ResolvableType returnType;
 
-		public AsyncResultMethodParameter(Object returnValue) {
+		public AsyncResultMethodParameter(@Nullable Object returnValue) {
 			super(-1);
 			this.returnValue = returnValue;
 			this.returnType = ResolvableType.forType(super.getGenericParameterType()).getGeneric();

spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java

@@ -54,6 +54,7 @@ public class SimpMessagingTemplate extends AbstractMessageSendingTemplate<String
 
 	private volatile long sendTimeout = -1;
 
+	@Nullable
 	private MessageHeaderInitializer headerInitializer;
 
 

spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java

@@ -26,6 +26,7 @@ import java.util.Map;
 import java.util.Set;
 
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
+import org.springframework.context.ApplicationContext;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.EmbeddedValueResolverAware;
 import org.springframework.context.SmartLifecycle;
@@ -305,8 +306,9 @@ public class SimpAnnotationMethodMessageHandler extends AbstractMethodMessageHan
 
 
 	protected List<HandlerMethodArgumentResolver> initArgumentResolvers() {
-		ConfigurableBeanFactory beanFactory = (getApplicationContext() instanceof ConfigurableApplicationContext ?
-				((ConfigurableApplicationContext) getApplicationContext()).getBeanFactory() : null);
+		ApplicationContext context = getApplicationContext();
+		ConfigurableBeanFactory beanFactory = (context instanceof ConfigurableApplicationContext ?
+				((ConfigurableApplicationContext) context).getBeanFactory() : null);
 
 		List<HandlerMethodArgumentResolver> resolvers = new ArrayList<>();
 

spring-messaging/src/main/java/org/springframework/messaging/support/IdTimestampMessageHeaderInitializer.java

@@ -16,8 +16,6 @@
 
 package org.springframework.messaging.support;
 
-import java.util.UUID;
-
 import org.springframework.lang.Nullable;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.IdGenerator;
@@ -31,6 +29,10 @@ import org.springframework.util.IdGenerator;
  */
 public class IdTimestampMessageHeaderInitializer implements MessageHeaderInitializer {
 
+	private static final IdGenerator ID_VALUE_NONE_GENERATOR = () -> MessageHeaders.ID_VALUE_NONE;
+
+
+	@Nullable
 	private IdGenerator idGenerator;
 
 	private boolean enableTimestamp;
@@ -41,20 +43,12 @@ public class IdTimestampMessageHeaderInitializer implements MessageHeaderInitial
 	 * instances with.
 	 * <p>By default this property is set to {@code null} in which case the default
 	 * IdGenerator of {@link org.springframework.messaging.MessageHeaders} is used.
-	 * <p>To have no id's generated at all, see {@link #setDisableIdGeneration()}.
+	 * <p>To have no ids generated at all, see {@link #setDisableIdGeneration()}.
 	 */
 	public void setIdGenerator(@Nullable IdGenerator idGenerator) {
 		this.idGenerator = idGenerator;
 	}
 
-	/**
-	 * A shortcut for calling {@link #setIdGenerator(org.springframework.util.IdGenerator)}
-	 * with an id generation strategy to disable id generation completely.
-	 */
-	public void setDisableIdGeneration() {
-		this.idGenerator = ID_VALUE_NONE_GENERATOR;
-	}
-
 	/**
 	 * Return the configured {@code IdGenerator}, if any.
 	 */
@@ -63,6 +57,14 @@ public class IdTimestampMessageHeaderInitializer implements MessageHeaderInitial
 		return this.idGenerator;
 	}
 
+	/**
+	 * A shortcut for calling {@link #setIdGenerator} with an id generation strategy
+	 * to disable id generation completely.
+	 */
+	public void setDisableIdGeneration() {
+		this.idGenerator = ID_VALUE_NONE_GENERATOR;
+	}
+
 	/**
 	 * Whether to enable the automatic addition of the
 	 * {@link org.springframework.messaging.MessageHeaders#TIMESTAMP} header on
@@ -90,12 +92,4 @@ public class IdTimestampMessageHeaderInitializer implements MessageHeaderInitial
 		headerAccessor.setEnableTimestamp(isEnableTimestamp());
 	}
 
-
-	private static final IdGenerator ID_VALUE_NONE_GENERATOR = new IdGenerator() {
-		@Override
-		public UUID generateId() {
-			return MessageHeaders.ID_VALUE_NONE;
-		}
-	};
-
 }

spring-messaging/src/main/java/org/springframework/messaging/tcp/reactor/AbstractMonoToListenableFutureAdapter.java

@@ -24,6 +24,7 @@ import java.util.concurrent.TimeoutException;
 import reactor.core.publisher.Mono;
 import reactor.core.publisher.MonoProcessor;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.concurrent.FailureCallback;
 import org.springframework.util.concurrent.ListenableFuture;
@@ -67,12 +68,14 @@ abstract class AbstractMonoToListenableFutureAdapter<S, T> implements Listenable
 
 
 	@Override
+	@Nullable
 	public T get() throws InterruptedException {
 		S result = this.monoProcessor.block();
 		return adapt(result);
 	}
 
 	@Override
+	@Nullable
 	public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
 		Assert.notNull(unit, "TimeUnit must not be null");
 		Duration duration = Duration.ofMillis(TimeUnit.MILLISECONDS.convert(timeout, unit));
@@ -111,6 +114,7 @@ abstract class AbstractMonoToListenableFutureAdapter<S, T> implements Listenable
 	}
 
 
-	protected abstract T adapt(S result);
+	@Nullable
+	protected abstract T adapt(@Nullable S result);
 
 }

spring-messaging/src/main/java/org/springframework/messaging/tcp/reactor/MonoToListenableFutureAdapter.java

@@ -18,6 +18,8 @@ package org.springframework.messaging.tcp.reactor;
 
 import reactor.core.publisher.Mono;
 
+import org.springframework.lang.Nullable;
+
 /**
  * A Mono-to-ListenableFuture adapter where the source and the target from
  * the Promise and the ListenableFuture respectively are of the same type.
@@ -33,7 +35,7 @@ class MonoToListenableFutureAdapter<T> extends AbstractMonoToListenableFutureAda
 	}
 
 	@Override
-	protected T adapt(T result) {
+	protected T adapt(@Nullable T result) {
 		return result;
 	}
 

spring-orm/src/main/java/org/springframework/orm/jpa/vendor/AbstractJpaVendorAdapter.java

@@ -36,6 +36,7 @@ public abstract class AbstractJpaVendorAdapter implements JpaVendorAdapter {
 
 	private Database database = Database.DEFAULT;
 
+	@Nullable
 	private String databasePlatform;
 
 	private boolean generateDdl = false;
@@ -47,14 +48,13 @@ public abstract class AbstractJpaVendorAdapter implements JpaVendorAdapter {
 	 * Specify the target database to operate on, as a value of the {@code Database} enum:
 	 * DB2, DERBY, H2, HSQL, INFORMIX, MYSQL, ORACLE, POSTGRESQL, SQL_SERVER, SYBASE
 	 */
-	public void setDatabase(@Nullable Database database) {
+	public void setDatabase(Database database) {
 		this.database = database;
 	}
 
 	/**
 	 * Return the target database to operate on.
 	 */
-	@Nullable
 	protected Database getDatabase() {
 		return this.database;
 	}

spring-orm/src/main/java/org/springframework/orm/jpa/vendor/EclipseLinkJpaVendorAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -65,7 +65,7 @@ public class EclipseLinkJpaVendorAdapter extends AbstractJpaVendorAdapter {
 		if (getDatabasePlatform() != null) {
 			jpaProperties.put(PersistenceUnitProperties.TARGET_DATABASE, getDatabasePlatform());
 		}
-		else if (getDatabase() != null) {
+		else {
 			String targetDatabase = determineTargetDatabaseName(getDatabase());
 			if (targetDatabase != null) {
 				jpaProperties.put(PersistenceUnitProperties.TARGET_DATABASE, targetDatabase);

spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaVendorAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -18,7 +18,6 @@ package org.springframework.orm.jpa.vendor;
 
 import java.util.HashMap;
 import java.util.Map;
-
 import javax.persistence.EntityManager;
 import javax.persistence.EntityManagerFactory;
 import javax.persistence.spi.PersistenceProvider;
@@ -117,7 +116,7 @@ public class HibernateJpaVendorAdapter extends AbstractJpaVendorAdapter {
 		if (getDatabasePlatform() != null) {
 			jpaProperties.put(AvailableSettings.DIALECT, getDatabasePlatform());
 		}
-		else if (getDatabase() != null) {
+		else {
 			Class<?> databaseDialectClass = determineDatabaseDialectClass(getDatabase());
 			if (databaseDialectClass != null) {
 				jpaProperties.put(AvailableSettings.DIALECT, databaseDialectClass.getName());

spring-web/src/main/java/org/springframework/http/converter/AbstractHttpMessageConverter.java

@@ -54,6 +54,7 @@ public abstract class AbstractHttpMessageConverter<T> implements HttpMessageConv
 
 	private List<MediaType> supportedMediaTypes = Collections.emptyList();
 
+	@Nullable
 	private Charset defaultCharset;
 
 

spring-web/src/main/java/org/springframework/web/bind/WebDataBinder.java

@@ -75,8 +75,10 @@ public class WebDataBinder extends DataBinder {
 	 */
 	public static final String DEFAULT_FIELD_DEFAULT_PREFIX = "!";
 
+	@Nullable
 	private String fieldMarkerPrefix = DEFAULT_FIELD_MARKER_PREFIX;
 
+	@Nullable
 	private String fieldDefaultPrefix = DEFAULT_FIELD_DEFAULT_PREFIX;
 
 	private boolean bindEmptyMultipartFiles = true;
@@ -124,13 +126,14 @@ public class WebDataBinder extends DataBinder {
 	 * detect an empty field and automatically reset its value.
 	 * @see #DEFAULT_FIELD_MARKER_PREFIX
 	 */
-	public void setFieldMarkerPrefix(String fieldMarkerPrefix) {
+	public void setFieldMarkerPrefix(@Nullable String fieldMarkerPrefix) {
 		this.fieldMarkerPrefix = fieldMarkerPrefix;
 	}
 
 	/**
 	 * Return the prefix for parameters that mark potentially empty fields.
 	 */
+	@Nullable
 	public String getFieldMarkerPrefix() {
 		return this.fieldMarkerPrefix;
 	}
@@ -149,13 +152,14 @@ public class WebDataBinder extends DataBinder {
 	 * marker for the given field.
 	 * @see #DEFAULT_FIELD_DEFAULT_PREFIX
 	 */
-	public void setFieldDefaultPrefix(String fieldDefaultPrefix) {
+	public void setFieldDefaultPrefix(@Nullable String fieldDefaultPrefix) {
 		this.fieldDefaultPrefix = fieldDefaultPrefix;
 	}
 
 	/**
 	 * Return the prefix for parameters that mark default fields.
 	 */
+	@Nullable
 	public String getFieldDefaultPrefix() {
 		return this.fieldDefaultPrefix;
 	}

spring-web/src/main/java/org/springframework/web/context/support/AbstractRefreshableWebApplicationContext.java

@@ -117,7 +117,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	@Override
 	public void setServletConfig(@Nullable ServletConfig servletConfig) {
 		this.servletConfig = servletConfig;
-		if (this.servletContext == null) {
+		if (servletConfig != null && this.servletContext == null) {
 			setServletContext(servletConfig.getServletContext());
 		}
 	}
@@ -131,7 +131,9 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	@Override
 	public void setNamespace(@Nullable String namespace) {
 		this.namespace = namespace;
-		setDisplayName(namespace != null ? "WebApplicationContext for namespace '" + namespace + "'" : null);
+		if (namespace != null) {
+			setDisplayName("WebApplicationContext for namespace '" + namespace + "'");
+		}
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/web/context/support/StaticWebApplicationContext.java

@@ -93,7 +93,7 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	@Override
 	public void setServletConfig(@Nullable ServletConfig servletConfig) {
 		this.servletConfig = servletConfig;
-		if (this.servletContext == null) {
+		if (servletConfig != null && this.servletContext == null) {
 			this.servletContext = servletConfig.getServletContext();
 		}
 	}
@@ -107,7 +107,9 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	@Override
 	public void setNamespace(@Nullable String namespace) {
 		this.namespace = namespace;
-		setDisplayName(namespace != null ? "WebApplicationContext for namespace '" + namespace + "'" : null);
+		if (namespace != null) {
+			setDisplayName("WebApplicationContext for namespace '" + namespace + "'");
+		}
 	}
 
 	@Override

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/RedirectView.java

@@ -62,6 +62,7 @@ public class RedirectView extends AbstractUrlBasedView {
 
 	private boolean propagateQuery = false;
 
+	@Nullable
 	private String[] hosts;
 
 
@@ -111,17 +112,14 @@ public class RedirectView extends AbstractUrlBasedView {
 	 * {@link HttpStatus#TEMPORARY_REDIRECT} or
 	 * {@link HttpStatus#PERMANENT_REDIRECT}.
 	 */
-	public void setStatusCode(@Nullable HttpStatus statusCode) {
-		if (statusCode != null) {
-			Assert.isTrue(statusCode.is3xxRedirection(), "Must be a redirection (3xx status code)");
-		}
+	public void setStatusCode(HttpStatus statusCode) {
+		Assert.isTrue(statusCode.is3xxRedirection(), "Must be a redirection (3xx status code)");
 		this.statusCode = statusCode;
 	}
 
 	/**
 	 * Get the redirect status code to use.
 	 */
-	@Nullable
 	public HttpStatus getStatusCode() {
 		return this.statusCode;
 	}
@@ -150,13 +148,14 @@ public class RedirectView extends AbstractUrlBasedView {
 	 * <p>If not set (the default) all redirect URLs are encoded.
 	 * @param hosts one or more application hosts
 	 */
-	public void setHosts(String... hosts) {
+	public void setHosts(@Nullable String... hosts) {
 		this.hosts = hosts;
 	}
 
 	/**
 	 * Return the configured application hosts.
 	 */
+	@Nullable
 	public String[] getHosts() {
 		return this.hosts;
 	}
@@ -165,9 +164,6 @@ public class RedirectView extends AbstractUrlBasedView {
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		super.afterPropertiesSet();
-		if (getStatusCode() == null) {
-			throw new IllegalArgumentException("Property 'statusCode' is required");
-		}
 	}
 
 
@@ -185,8 +181,8 @@ public class RedirectView extends AbstractUrlBasedView {
 	 * Convert model to request parameters and redirect to the given URL.
 	 */
 	@Override
-	protected Mono<Void> renderInternal(Map<String, Object> model, MediaType contentType,
-			ServerWebExchange exchange) {
+	protected Mono<Void> renderInternal(
+			Map<String, Object> model, @Nullable MediaType contentType, ServerWebExchange exchange) {
 
 		String targetUrl = createTargetUrl(model, exchange);
 		return sendRedirect(targetUrl, exchange);
@@ -296,10 +292,7 @@ public class RedirectView extends AbstractUrlBasedView {
 		ServerHttpResponse response = exchange.getResponse();
 		String encodedURL = (isRemoteHost(targetUrl) ? targetUrl : response.encodeUrl(targetUrl));
 		response.getHeaders().setLocation(URI.create(encodedURL));
-		HttpStatus status = getStatusCode();
-		if (status != null) {
-			response.setStatusCode(status);
-		}
+		response.setStatusCode(getStatusCode());
 		return Mono.empty();
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/CookieLocaleResolver.java

@@ -105,8 +105,6 @@ public class CookieLocaleResolver extends CookieGenerator implements LocaleConte
 	 * Specify whether this resolver's cookies should be compliant with BCP 47
 	 * language tags instead of Java's legacy locale specification format.
 	 * The default is {@code false}.
-	 * <p>Note: This mode requires JDK 7 or higher. Set this flag to {@code true}
-	 * for BCP 47 compliance on JDK 7+ only.
 	 * @since 4.3
 	 * @see Locale#forLanguageTag(String)
 	 * @see Locale#toLanguageTag()
@@ -182,43 +180,48 @@ public class CookieLocaleResolver extends CookieGenerator implements LocaleConte
 
 	private void parseLocaleCookieIfNecessary(HttpServletRequest request) {
 		if (request.getAttribute(LOCALE_REQUEST_ATTRIBUTE_NAME) == null) {
-			// Retrieve and parse cookie value.
-			Cookie cookie = WebUtils.getCookie(request, getCookieName());
 			Locale locale = null;
 			TimeZone timeZone = null;
-			if (cookie != null) {
-				String value = cookie.getValue();
-				String localePart = value;
-				String timeZonePart = null;
-				int spaceIndex = localePart.indexOf(' ');
-				if (spaceIndex != -1) {
-					localePart = value.substring(0, spaceIndex);
-					timeZonePart = value.substring(spaceIndex + 1);
-				}
-				try {
-					locale = (!"-".equals(localePart) ? parseLocaleValue(localePart) : null);
-					if (timeZonePart != null) {
-						timeZone = StringUtils.parseTimeZoneString(timeZonePart);
+
+			// Retrieve and parse cookie value.
+			String cookieName = getCookieName();
+			if (cookieName != null) {
+				Cookie cookie = WebUtils.getCookie(request, cookieName);
+				if (cookie != null) {
+					String value = cookie.getValue();
+					String localePart = value;
+					String timeZonePart = null;
+					int spaceIndex = localePart.indexOf(' ');
+					if (spaceIndex != -1) {
+						localePart = value.substring(0, spaceIndex);
+						timeZonePart = value.substring(spaceIndex + 1);
 					}
-				}
-				catch (IllegalArgumentException ex) {
-					if (request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) != null) {
-						// Error dispatch: ignore locale/timezone parse exceptions
-						if (logger.isDebugEnabled()) {
-							logger.debug("Ignoring invalid locale cookie '" + getCookieName() +
-									"' with value [" + value + "] due to error dispatch: " + ex.getMessage());
+					try {
+						locale = (!"-".equals(localePart) ? parseLocaleValue(localePart) : null);
+						if (timeZonePart != null) {
+							timeZone = StringUtils.parseTimeZoneString(timeZonePart);
 						}
 					}
-					else {
-						throw new IllegalStateException("Invalid locale cookie '" + getCookieName() +
-								"' with value [" + value + "]: " + ex.getMessage());
+					catch (IllegalArgumentException ex) {
+						if (request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) != null) {
+							// Error dispatch: ignore locale/timezone parse exceptions
+							if (logger.isDebugEnabled()) {
+								logger.debug("Ignoring invalid locale cookie '" + cookieName +
+										"' with value [" + value + "] due to error dispatch: " + ex.getMessage());
+							}
+						}
+						else {
+							throw new IllegalStateException("Invalid locale cookie '" + cookieName +
+									"' with value [" + value + "]: " + ex.getMessage());
+						}
+					}
+					if (logger.isDebugEnabled()) {
+						logger.debug("Parsed cookie value [" + cookie.getValue() + "] into locale '" + locale +
+								"'" + (timeZone != null ? " and time zone '" + timeZone.getID() + "'" : ""));
 					}
-				}
-				if (logger.isDebugEnabled()) {
-					logger.debug("Parsed cookie value [" + cookie.getValue() + "] into locale '" + locale +
-							"'" + (timeZone != null ? " and time zone '" + timeZone.getID() + "'" : ""));
 				}
 			}
+
 			request.setAttribute(LOCALE_REQUEST_ATTRIBUTE_NAME,
 					(locale != null ? locale : determineDefaultLocale(request)));
 			request.setAttribute(TIME_ZONE_REQUEST_ATTRIBUTE_NAME,

spring-webmvc/src/main/java/org/springframework/web/servlet/theme/CookieThemeResolver.java

@@ -88,11 +88,14 @@ public class CookieThemeResolver extends CookieGenerator implements ThemeResolve
 		}
 
 		// Retrieve cookie value from request.
-		Cookie cookie = WebUtils.getCookie(request, getCookieName());
-		if (cookie != null) {
-			String value = cookie.getValue();
-			if (StringUtils.hasText(value)) {
-				themeName = value;
+		String cookieName = getCookieName();
+		if (cookieName != null) {
+			Cookie cookie = WebUtils.getCookie(request, cookieName);
+			if (cookie != null) {
+				String value = cookie.getValue();
+				if (StringUtils.hasText(value)) {
+					themeName = value;
+				}
 			}
 		}