diff --git a/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceBuilder.java b/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceBuilder.java
index 930d4bc769d..f019402e21c 100644
--- a/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceBuilder.java
+++ b/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceBuilder.java
@@ -90,8 +90,8 @@ public class DataSourceBuilder {
 		ConfigurationPropertySource source = new MapConfigurationPropertySource(
 				this.properties);
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
-		aliases.addAlaises("url", "jdbc-url");
-		aliases.addAlaises("username", "user");
+		aliases.addAliases("url", "jdbc-url");
+		aliases.addAliases("username", "user");
 		Binder binder = new Binder(source.withAliases(aliases));
 		binder.bind(ConfigurationPropertyName.EMPTY, Bindable.ofInstance(result));
 	}
diff --git a/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/XADataSourceAutoConfiguration.java b/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/XADataSourceAutoConfiguration.java
index 11c9721c7ac..906d3f559b7 100644
--- a/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/XADataSourceAutoConfiguration.java
+++ b/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/XADataSourceAutoConfiguration.java
@@ -124,7 +124,7 @@ public class XADataSourceAutoConfiguration implements BeanClassLoaderAware {
 		source.put("url", this.properties.determineUrl());
 		source.putAll(dataSourceProperties.getXa().getProperties());
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
-		aliases.addAlaises("user", "username");
+		aliases.addAliases("user", "username");
 		return source.withAliases(aliases);
 	}
 
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationBeanFactoryMetaData.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationBeanFactoryMetaData.java
index 536ab0a2a6c..32f0bff7b48 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationBeanFactoryMetaData.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationBeanFactoryMetaData.java
@@ -41,7 +41,7 @@ public class ConfigurationBeanFactoryMetaData implements BeanFactoryPostProcesso
 
 	private ConfigurableListableBeanFactory beanFactory;
 
-	private Map<String, MetaData> beans = new HashMap<>();
+	private final Map<String, MetaData> beans = new HashMap<>();
 
 	@Override
 	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
@@ -96,9 +96,9 @@ public class ConfigurationBeanFactoryMetaData implements BeanFactoryPostProcesso
 
 	private static class MetaData {
 
-		private String bean;
+		private final String bean;
 
-		private String method;
+		private final String method;
 
 		MetaData(String bean, String method) {
 			this.bean = bean;
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java
index 7d718f7f8e9..8f765be23dd 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java
@@ -465,7 +465,7 @@ public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProc
 	 */
 	private static class ChainingValidator implements Validator {
 
-		private Validator[] validators;
+		private final Validator[] validators;
 
 		ChainingValidator(Validator... validators) {
 			Assert.notNull(validators, "Validators must not be null");
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BeanBinder.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BeanBinder.java
index c1889f800c5..3f06b8ba11b 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BeanBinder.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BeanBinder.java
@@ -29,7 +29,7 @@ interface BeanBinder {
 	/**
 	 * Return a bound bean instance or {@code null} if the {@link BeanBinder} does not
 	 * support the specified {@link Bindable}.
-	 * @param target the binable to bind
+	 * @param target the bindable to bind
 	 * @param hasKnownBindableProperties if this binder has known bindable elements. If
 	 * names from underlying {@link ConfigurationPropertySource} cannot be iterated this
 	 * method can be {@code false}, even though binding may ultimately succeed.
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindException.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindException.java
index ddf5d4ba62a..7f293b3f0bd 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindException.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindException.java
@@ -78,7 +78,7 @@ public class BindException extends RuntimeException implements OriginProvider {
 		StringBuilder message = new StringBuilder();
 		message.append("Failed to bind properties");
 		message.append(name == null ? "" : " under '" + name + "'");
-		message.append(" to " + target.getType());
+		message.append(" to ").append(target.getType());
 		return message.toString();
 	}
 
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindHandler.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindHandler.java
index b564b8eb373..3efd7391b1e 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindHandler.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindHandler.java
@@ -29,7 +29,7 @@ import org.springframework.boot.context.properties.source.ConfigurationPropertyN
 public interface BindHandler {
 
 	/**
-	 * Default no-op bind hander.
+	 * Default no-op bind handler.
 	 */
 	BindHandler DEFAULT = new BindHandler() {
 
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindResult.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindResult.java
index 72754f7bc3f..6182923abb5 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindResult.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/BindResult.java
@@ -161,7 +161,7 @@ public final class BindResult<T> {
 		if (value == null) {
 			return (BindResult<T>) UNBOUND;
 		}
-		return new BindResult<T>(value);
+		return new BindResult<>(value);
 	}
 
 }
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Bindable.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Bindable.java
index 14ea6408868..884b89db8d8 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Bindable.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Bindable.java
@@ -129,7 +129,7 @@ public final class Bindable<T> {
 	 * @return an updated {@link Bindable}
 	 */
 	public Bindable<T> withAnnotations(Annotation... annotations) {
-		return new Bindable<T>(this.type, this.boxedType, this.value,
+		return new Bindable<>(this.type, this.boxedType, this.value,
 				(annotations == null ? NO_ANNOTATIONS : annotations));
 	}
 
@@ -226,7 +226,7 @@ public final class Bindable<T> {
 			Class<?> wrapperType = Array.get(array, 0).getClass();
 			return ResolvableType.forClass(wrapperType);
 		}
-		if (resolved.isArray()) {
+		if (resolved != null && resolved.isArray()) {
 			return ResolvableType.forArrayComponent(box(type.getComponentType()));
 		}
 		return type;
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Binder.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Binder.java
index e31dcb840b7..cf338cbafca 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Binder.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Binder.java
@@ -287,7 +287,7 @@ public class Binder {
 	}
 
 	private Object bindBean(ConfigurationPropertyName name, Bindable<?> target,
-			BindHandler handler, Context context) throws Exception {
+			BindHandler handler, Context context) {
 		boolean hasKnownBindableProperties = context.streamSources()
 				.flatMap((s) -> s.filter(name::isAncestorOf).stream()).findAny()
 				.isPresent();
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/JavaBeanBinder.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/JavaBeanBinder.java
index adf03823988..ddd07fe373b 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/JavaBeanBinder.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/JavaBeanBinder.java
@@ -44,12 +44,12 @@ class JavaBeanBinder implements BeanBinder {
 			return null;
 		}
 		BeanSupplier<T> beanSupplier = bean.getSupplier(target);
-		boolean bound = bind(target, propertyBinder, bean, beanSupplier);
+		boolean bound = bind(propertyBinder, bean, beanSupplier);
 		return (bound ? beanSupplier.get() : null);
 	}
 
-	private <T> boolean bind(Bindable<T> target, BeanPropertyBinder propertyBinder,
-			Bean<T> bean, BeanSupplier<T> beanSupplier) {
+	private <T> boolean bind(BeanPropertyBinder propertyBinder, Bean<T> bean,
+			BeanSupplier<T> beanSupplier) {
 		boolean bound = false;
 		for (Map.Entry<String, BeanProperty> entry : bean.getProperties().entrySet()) {
 			bound |= bind(beanSupplier, propertyBinder, entry.getValue());
@@ -151,7 +151,7 @@ class JavaBeanBinder implements BeanBinder {
 
 		@SuppressWarnings("unchecked")
 		public BeanSupplier<T> getSupplier(Bindable<T> target) {
-			return new BeanSupplier<T>(() -> {
+			return new BeanSupplier<>(() -> {
 				T instance = null;
 				if (target.getValue() != null) {
 					instance = target.getValue().get();
@@ -168,7 +168,7 @@ class JavaBeanBinder implements BeanBinder {
 				boolean useExistingValueForType) {
 			Class<?> type = bindable.getType().resolve();
 			Supplier<T> value = bindable.getValue();
-			if (value == null && !isInstantiatable(type)) {
+			if (value == null && !isInstantiable(type)) {
 				return null;
 			}
 			if (useExistingValueForType && value != null) {
@@ -183,7 +183,7 @@ class JavaBeanBinder implements BeanBinder {
 			return (Bean<T>) bean;
 		}
 
-		private static boolean isInstantiatable(Class<?> type) {
+		private static boolean isInstantiable(Class<?> type) {
 			if (type.isInterface()) {
 				return false;
 			}
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/MapBinder.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/MapBinder.java
index 37420371e40..c014b48221a 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/MapBinder.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/MapBinder.java
@@ -84,7 +84,7 @@ class MapBinder extends AggregateBinder<Map<Object, Object>> {
 		public void bindEntries(ConfigurationPropertySource source,
 				Map<Object, Object> map) {
 			for (ConfigurationPropertyName name : source) {
-				Bindable<?> valueBindable = getValueBindable(source, name);
+				Bindable<?> valueBindable = getValueBindable(name);
 				ConfigurationPropertyName entryName = getEntryName(source, name);
 				Object key = getContext().getConversionService()
 						.convert(getKeyName(entryName), this.keyType);
@@ -93,8 +93,7 @@ class MapBinder extends AggregateBinder<Map<Object, Object>> {
 			}
 		}
 
-		private Bindable<?> getValueBindable(ConfigurationPropertySource source,
-				ConfigurationPropertyName name) {
+		private Bindable<?> getValueBindable(ConfigurationPropertyName name) {
 			if (isMultiElementName(name) && isValueTreatedAsNestedMap()) {
 				return Bindable.of(this.mapType);
 			}
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/PropertySourcesPlaceholdersResolver.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/PropertySourcesPlaceholdersResolver.java
index a168d651eb3..c18f8210a48 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/PropertySourcesPlaceholdersResolver.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/PropertySourcesPlaceholdersResolver.java
@@ -33,9 +33,9 @@ import org.springframework.util.SystemPropertyUtils;
  */
 public class PropertySourcesPlaceholdersResolver implements PlaceholdersResolver {
 
-	private PropertySources sources;
+	private final PropertySources sources;
 
-	private PropertyPlaceholderHelper helper;
+	private final PropertyPlaceholderHelper helper;
 
 	public PropertySourcesPlaceholdersResolver(Environment environment) {
 		this(getSources(environment), null);
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/validation/ValidationBindHandler.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/validation/ValidationBindHandler.java
index c1a64269d72..239dc2f6ba1 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/validation/ValidationBindHandler.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/validation/ValidationBindHandler.java
@@ -46,7 +46,7 @@ public class ValidationBindHandler extends AbstractBindHandler {
 
 	private boolean validate;
 
-	private Set<ConfigurationProperty> boundProperties = new LinkedHashSet<>();
+	private final Set<ConfigurationProperty> boundProperties = new LinkedHashSet<>();
 
 	public ValidationBindHandler(Validator... validators) {
 		super();
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyName.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyName.java
index 1e2d133e993..f174b08f3bf 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyName.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyName.java
@@ -141,7 +141,7 @@ public final class ConfigurationPropertyName
 	 * Returns {@code true} if this element is an ancestor (immediate or nested parent) or
 	 * the specified name.
 	 * @param name the name to check
-	 * @return {@code true} if this name is an ancessor
+	 * @return {@code true} if this name is an ancestor
 	 */
 	public boolean isAncestorOf(ConfigurationPropertyName name) {
 		ConfigurationPropertyName candidate = (name == null ? null : name.getParent());
@@ -231,8 +231,8 @@ public final class ConfigurationPropertyName
 	public static ConfigurationPropertyName of(String name)
 			throws IllegalArgumentException {
 		Assert.notNull(name, "Name must not be null");
-		Assert.isTrue(!name.toString().startsWith("."), "Name must not start with '.'");
-		Assert.isTrue(!name.toString().endsWith("."), "Name must not end with '.'");
+		Assert.isTrue(!name.startsWith("."), "Name must not start with '.'");
+		Assert.isTrue(!name.endsWith("."), "Name must not end with '.'");
 		if (StringUtils.isEmpty(name)) {
 			return EMPTY;
 		}
@@ -308,7 +308,7 @@ public final class ConfigurationPropertyName
 
 		@Override
 		public String toString() {
-			String string = getValue(Form.CONFIGURATION).toString();
+			String string = getValue(Form.CONFIGURATION);
 			return (this.indexed ? "[" + string + "]" : string);
 		}
 
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliases.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliases.java
index 022c124cdb2..f668bae35f3 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliases.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliases.java
@@ -26,7 +26,7 @@ import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 
 /**
- * Maintains a mapping of {@link ConfigurationPropertyName} alaises.
+ * Maintains a mapping of {@link ConfigurationPropertyName} aliases.
  *
  * @author Phillip Webb
  * @author Madhura Bhave
@@ -41,23 +41,23 @@ public final class ConfigurationPropertyNameAliases {
 	}
 
 	public ConfigurationPropertyNameAliases(String name, String... aliases) {
-		addAlaises(name, aliases);
+		addAliases(name, aliases);
 	}
 
 	public ConfigurationPropertyNameAliases(ConfigurationPropertyName name,
 			ConfigurationPropertyName... aliases) {
-		addAlaises(name, aliases);
+		addAliases(name, aliases);
 	}
 
-	public void addAlaises(String name, String... aliases) {
+	public void addAliases(String name, String... aliases) {
 		Assert.notNull(name, "Name must not be null");
 		Assert.notNull(aliases, "Aliases must not be null");
-		addAlaises(ConfigurationPropertyName.of(name),
+		addAliases(ConfigurationPropertyName.of(name),
 				Arrays.stream(aliases).map(ConfigurationPropertyName::of)
 						.toArray(ConfigurationPropertyName[]::new));
 	}
 
-	public void addAlaises(ConfigurationPropertyName name,
+	public void addAliases(ConfigurationPropertyName name,
 			ConfigurationPropertyName... aliases) {
 		Assert.notNull(name, "Name must not be null");
 		Assert.notNull(aliases, "Aliases must not be null");
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySource.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySource.java
index 4f75405787b..d2109a62a78 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySource.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySource.java
@@ -77,7 +77,7 @@ public interface ConfigurationPropertySource extends Iterable<ConfigurationPrope
 	/**
 	 * Return a variant of this source that supports name aliases.
 	 * @param aliases a function that returns a stream of aliases for any given name
-	 * @return a {@link ConfigurationPropertySource} instance supporting name alaises
+	 * @return a {@link ConfigurationPropertySource} instance supporting name aliases
 	 */
 	default ConfigurationPropertySource withAliases(
 			ConfigurationPropertyNameAliases aliases) {
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySources.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySources.java
index be7fae3f467..c1690f6c84c 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySources.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySources.java
@@ -47,7 +47,7 @@ public class ConfigurationPropertySources
 	/**
 	 * The name of the {@link PropertySource} {@link #adapt adapter}.
 	 */
-	public static final String PROPERTY_SOURCE_NAME = "configurationPropertes";
+	public static final String PROPERTY_SOURCE_NAME = "configurationProperties";
 
 	private final PropertySources propertySources;
 
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/DefaultPropertyMapper.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/DefaultPropertyMapper.java
index 0718e69c349..00360a81cd1 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/DefaultPropertyMapper.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/DefaultPropertyMapper.java
@@ -37,9 +37,9 @@ class DefaultPropertyMapper implements PropertyMapper {
 
 	public static final PropertyMapper INSTANCE = new DefaultPropertyMapper();
 
-	private Cache<ConfigurationPropertyName> configurationPropertySourceCache = new Cache<>();
+	private final Cache<ConfigurationPropertyName> configurationPropertySourceCache = new Cache<>();
 
-	private Cache<String> propertySourceCache = new Cache<>();
+	private final Cache<String> propertySourceCache = new Cache<>();
 
 	private final ConfigurationPropertyNameBuilder nameBuilder = new ConfigurationPropertyNameBuilder();
 
@@ -59,12 +59,7 @@ class DefaultPropertyMapper implements PropertyMapper {
 	@Override
 	public List<PropertyMapping> map(PropertySource<?> propertySource,
 			String propertySourceName) {
-		List<PropertyMapping> mapping = this.propertySourceCache.get(propertySourceName);
-		if (mapping == null) {
-			mapping = tryMap(propertySourceName);
-			this.propertySourceCache.put(propertySourceName, mapping);
-		}
-		return mapping;
+		return this.propertySourceCache.computeIfAbsent(propertySourceName, this::tryMap);
 	}
 
 	private List<PropertyMapping> tryMap(String propertySourceName) {
@@ -94,10 +89,7 @@ class DefaultPropertyMapper implements PropertyMapper {
 
 		@Override
 		protected boolean removeEldestEntry(Map.Entry<K, List<PropertyMapping>> eldest) {
-			if (size() < this.capacity) {
-				return false;
-			}
-			return true;
+			return size() >= this.capacity;
 
 		}
 
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/MapConfigurationPropertySource.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/MapConfigurationPropertySource.java
index d659e540f21..4334b571ffb 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/MapConfigurationPropertySource.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/MapConfigurationPropertySource.java
@@ -60,7 +60,7 @@ public class MapConfigurationPropertySource implements ConfigurationPropertySour
 	}
 
 	/**
-	 * Add all enties from the specified map.
+	 * Add all entries from the specified map.
 	 * @param map the source map
 	 */
 	public void putAll(Map<?, ?> map) {
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/PropertySourceConfigurationPropertySource.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/PropertySourceConfigurationPropertySource.java
index 696ea9668f0..8bc5856e854 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/PropertySourceConfigurationPropertySource.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/PropertySourceConfigurationPropertySource.java
@@ -145,7 +145,7 @@ class PropertySourceConfigurationPropertySource implements ConfigurationProperty
 			return names;
 		}
 		List<PropertyMapping> mappings = getPropertyMappings();
-		names = new ArrayList<ConfigurationPropertyName>(mappings.size());
+		names = new ArrayList<>(mappings.size());
 		for (PropertyMapping mapping : mappings) {
 			names.add(mapping.getConfigurationPropertyName());
 		}
@@ -167,7 +167,7 @@ class PropertySourceConfigurationPropertySource implements ConfigurationProperty
 		}
 		String[] names = ((EnumerablePropertySource<?>) this.propertySource)
 				.getPropertyNames();
-		mappings = new ArrayList<PropertyMapping>(names.length);
+		mappings = new ArrayList<>(names.length);
 		for (String name : names) {
 			mappings.addAll(this.mapper.map(this.propertySource, name));
 		}
@@ -238,8 +238,6 @@ class PropertySourceConfigurationPropertySource implements ConfigurationProperty
 
 	private static class Cache {
 
-		private ConfigurationPropertyName knownMissingName;
-
 		private List<ConfigurationPropertyName> names;
 
 		private List<PropertyMapping> mappings;
diff --git a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SystemEnvironmentPropertyMapper.java b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SystemEnvironmentPropertyMapper.java
index c95e56eccad..73b51ed7e4f 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SystemEnvironmentPropertyMapper.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SystemEnvironmentPropertyMapper.java
@@ -45,7 +45,7 @@ import org.springframework.util.StringUtils;
  */
 class SystemEnvironmentPropertyMapper implements PropertyMapper {
 
-	public static PropertyMapper INSTANCE = new SystemEnvironmentPropertyMapper();
+	public static final PropertyMapper INSTANCE = new SystemEnvironmentPropertyMapper();
 
 	private final ConfigurationPropertyNameBuilder nameBuilder = new ConfigurationPropertyNameBuilder(
 			this::createElement);
@@ -104,10 +104,9 @@ class SystemEnvironmentPropertyMapper implements PropertyMapper {
 	}
 
 	private String convertName(ConfigurationPropertyName configurationPropertyName) {
-		String propertyName = configurationPropertyName.stream()
+		return configurationPropertyName.stream()
 				.map(name -> name.getValue(Form.UNIFORM).toUpperCase())
 				.collect(Collectors.joining("_"));
-		return propertyName;
 	}
 
 	private boolean isListShortcutPossible(ConfigurationPropertyName name) {
diff --git a/spring-boot/src/main/java/org/springframework/boot/origin/TextResourceOrigin.java b/spring-boot/src/main/java/org/springframework/boot/origin/TextResourceOrigin.java
index 851f6bb5dd0..deaafadb1e7 100644
--- a/spring-boot/src/main/java/org/springframework/boot/origin/TextResourceOrigin.java
+++ b/spring-boot/src/main/java/org/springframework/boot/origin/TextResourceOrigin.java
@@ -86,7 +86,7 @@ public class TextResourceOrigin implements Origin {
 		result.append(this.resource == null ? "unknown resource [?]"
 				: this.resource.getDescription());
 		if (this.location != null) {
-			result.append(":" + this.location);
+			result.append(":").append(this.location);
 		}
 		return result.toString();
 	}
diff --git a/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliasesTests.java b/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliasesTests.java
index c68b303a901..551e6eec388 100644
--- a/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliasesTests.java
+++ b/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliasesTests.java
@@ -62,7 +62,7 @@ public class ConfigurationPropertyNameAliasesTests {
 	@Test
 	public void addAliasesFromStringShouldAddMapping() throws Exception {
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
-		aliases.addAlaises("foo", "bar", "baz");
+		aliases.addAliases("foo", "bar", "baz");
 		assertThat(aliases.getAliases(ConfigurationPropertyName.of("foo")))
 				.containsExactly(ConfigurationPropertyName.of("bar"),
 						ConfigurationPropertyName.of("baz"));
@@ -71,7 +71,7 @@ public class ConfigurationPropertyNameAliasesTests {
 	@Test
 	public void addAlaisesFromNameShouldAddMapping() throws Exception {
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
-		aliases.addAlaises(ConfigurationPropertyName.of("foo"),
+		aliases.addAliases(ConfigurationPropertyName.of("foo"),
 				ConfigurationPropertyName.of("bar"), ConfigurationPropertyName.of("baz"));
 		assertThat(aliases.getAliases(ConfigurationPropertyName.of("foo")))
 				.containsExactly(ConfigurationPropertyName.of("bar"),
@@ -81,8 +81,8 @@ public class ConfigurationPropertyNameAliasesTests {
 	@Test
 	public void addWhenHasExistingShouldAddAdditionalMappings() throws Exception {
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
-		aliases.addAlaises("foo", "bar");
-		aliases.addAlaises("foo", "baz");
+		aliases.addAliases("foo", "bar");
+		aliases.addAliases("foo", "baz");
 		assertThat(aliases.getAliases(ConfigurationPropertyName.of("foo")))
 				.containsExactly(ConfigurationPropertyName.of("bar"),
 						ConfigurationPropertyName.of("baz"));
@@ -97,7 +97,7 @@ public class ConfigurationPropertyNameAliasesTests {
 	@Test
 	public void getAliasesWhenMappedShouldReturnMapping() throws Exception {
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
-		aliases.addAlaises("foo", "bar");
+		aliases.addAliases("foo", "bar");
 		assertThat(aliases.getAliases(ConfigurationPropertyName.of("foo")))
 				.containsExactly(ConfigurationPropertyName.of("bar"));
 	}
@@ -105,8 +105,8 @@ public class ConfigurationPropertyNameAliasesTests {
 	@Test
 	public void getNameForAliasWhenHasMappingShouldReturnName() throws Exception {
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
-		aliases.addAlaises("foo", "bar");
-		aliases.addAlaises("foo", "baz");
+		aliases.addAliases("foo", "bar");
+		aliases.addAliases("foo", "baz");
 		assertThat((Object) aliases.getNameForAlias(ConfigurationPropertyName.of("bar")))
 				.isEqualTo(ConfigurationPropertyName.of("foo"));
 		assertThat((Object) aliases.getNameForAlias(ConfigurationPropertyName.of("baz")))
@@ -116,7 +116,7 @@ public class ConfigurationPropertyNameAliasesTests {
 	@Test
 	public void getNameForAliasWhenNotMappedShouldReturnNull() throws Exception {
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
-		aliases.addAlaises("foo", "bar");
+		aliases.addAliases("foo", "bar");
 		assertThat((Object) aliases.getNameForAlias(ConfigurationPropertyName.of("baz")))
 				.isNull();
 	}