Nullability refinements and related polishing

spring-context/src/main/java/org/springframework/ui/ConcurrentModel.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -66,7 +66,8 @@ public ConcurrentModel(Object attributeValue) {
 
 
 	@Override
-	public Object put(String key, Object value) {
+	@Nullable
+	public Object put(String key, @Nullable Object value) {
 		if (value != null) {
 			return super.put(key, value);
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -299,7 +299,7 @@ protected V execute(@Nullable Reference<K, V> ref, @Nullable Entry<K, V> entry,
 
 	@Override
 	@Nullable
-	public V remove(Object key) {
+	public V remove(@Nullable Object key) {
 		return doTask(key, new Task<V>(TaskOption.RESTRUCTURE_AFTER, TaskOption.SKIP_IF_EMPTY) {
 			@Override
 			@Nullable
@@ -316,7 +316,7 @@ protected V execute(@Nullable Reference<K, V> ref, @Nullable Entry<K, V> entry)
 	}
 
 	@Override
-	public boolean remove(Object key, final Object value) {
+	public boolean remove(@Nullable Object key, final @Nullable Object value) {
 		Boolean result = doTask(key, new Task<Boolean>(TaskOption.RESTRUCTURE_AFTER, TaskOption.SKIP_IF_EMPTY) {
 			@Override
 			protected Boolean execute(@Nullable Reference<K, V> ref, @Nullable Entry<K, V> entry) {
@@ -333,7 +333,7 @@ protected Boolean execute(@Nullable Reference<K, V> ref, @Nullable Entry<K, V> e
 	}
 
 	@Override
-	public boolean replace(K key, final V oldValue, final V newValue) {
+	public boolean replace(@Nullable K key, final @Nullable V oldValue, final @Nullable V newValue) {
 		Boolean result = doTask(key, new Task<Boolean>(TaskOption.RESTRUCTURE_BEFORE, TaskOption.SKIP_IF_EMPTY) {
 			@Override
 			protected Boolean execute(@Nullable Reference<K, V> ref, @Nullable Entry<K, V> entry) {
@@ -349,7 +349,7 @@ protected Boolean execute(@Nullable Reference<K, V> ref, @Nullable Entry<K, V> e
 
 	@Override
 	@Nullable
-	public V replace(K key, final V value) {
+	public V replace(@Nullable K key, final @Nullable V value) {
 		return doTask(key, new Task<V>(TaskOption.RESTRUCTURE_BEFORE, TaskOption.SKIP_IF_EMPTY) {
 			@Override
 			@Nullable

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -28,9 +28,11 @@
 import org.springframework.lang.Nullable;
 
 /**
- * Utility class for working with Strings that have placeholder values in them. A placeholder takes the form
- * {@code ${name}}. Using {@code PropertyPlaceholderHelper} these placeholders can be substituted for
- * user-supplied values. <p> Values for substitution can be supplied using a {@link Properties} instance or
+ * Utility class for working with Strings that have placeholder values in them.
+ * A placeholder takes the form {@code ${name}}. Using {@code PropertyPlaceholderHelper}
+ * these placeholders can be substituted for user-supplied values.
+ *
+ * <p>Values for substitution can be supplied using a {@link Properties} instance or
  * using a {@link PlaceholderResolver}.
  *
  * @author Juergen Hoeller

spring-web/src/test/java/org/springframework/http/converter/json/JsonbHttpMessageConverterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -72,7 +72,7 @@ public void canReadAndWriteMicroformats() {
 	public void readTyped() throws IOException {
 		String body = "{\"bytes\":[1,2],\"array\":[\"Foo\",\"Bar\"]," +
 				"\"number\":42,\"string\":\"Foo\",\"bool\":true,\"fraction\":42.0}";
-		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body.getBytes("UTF-8"));
+		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body.getBytes(StandardCharsets.UTF_8));
 		inputMessage.getHeaders().setContentType(new MediaType("application", "json"));
 		MyBean result = (MyBean) this.converter.read(MyBean.class, inputMessage);
 
@@ -90,7 +90,7 @@ public void readTyped() throws IOException {
 	public void readUntyped() throws IOException {
 		String body = "{\"bytes\":[1,2],\"array\":[\"Foo\",\"Bar\"]," +
 				"\"number\":42,\"string\":\"Foo\",\"bool\":true,\"fraction\":42.0}";
-		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body.getBytes("UTF-8"));
+		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body.getBytes(StandardCharsets.UTF_8));
 		inputMessage.getHeaders().setContentType(new MediaType("application", "json"));
 		HashMap<String, Object> result = (HashMap<String, Object>) this.converter.read(HashMap.class, inputMessage);
 		assertThat(result.get("string")).isEqualTo("Foo");
@@ -167,9 +167,9 @@ public void writeUTF16() throws IOException {
 	}
 
 	@Test
-	public void readInvalidJson() throws IOException {
+	public void readInvalidJson() {
 		String body = "FooBar";
-		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body.getBytes("UTF-8"));
+		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body.getBytes(StandardCharsets.UTF_8));
 		inputMessage.getHeaders().setContentType(new MediaType("application", "json"));
 		assertThatExceptionOfType(HttpMessageNotReadableException.class).isThrownBy(() ->
 				this.converter.read(MyBean.class, inputMessage));

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/HandlerMappingIntrospector.java

@@ -24,7 +24,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.BiFunction;
 import java.util.stream.Collectors;
 
@@ -83,8 +82,7 @@ public class HandlerMappingIntrospector
 	@Nullable
 	private List<HandlerMapping> handlerMappings;
 
-	@Nullable
-	private Map<HandlerMapping, PathPatternMatchableHandlerMapping> pathPatternHandlerMappings = new ConcurrentHashMap<>();
+	private Map<HandlerMapping, PathPatternMatchableHandlerMapping> pathPatternHandlerMappings = Collections.emptyMap();
 
 
 	/**
@@ -106,7 +104,7 @@ public HandlerMappingIntrospector(ApplicationContext context) {
 
 
 	/**
-	 * Return the configured or detected HandlerMapping's.
+	 * Return the configured or detected {@code HandlerMapping}s.
 	 */
 	public List<HandlerMapping> getHandlerMappings() {
 		return (this.handlerMappings != null ? this.handlerMappings : Collections.emptyList());
@@ -180,7 +178,6 @@ private <T> T doWithMatchingMapping(
 			BiFunction<HandlerMapping, HandlerExecutionChain, T> matchHandler) throws Exception {
 
 		Assert.notNull(this.handlerMappings, "Handler mappings not initialized");
-		Assert.notNull(this.pathPatternHandlerMappings, "Handler mappings with PathPatterns not initialized");
 
 		boolean parseRequestPath = !this.pathPatternHandlerMappings.isEmpty();
 		RequestPath previousPath = null;
@@ -247,6 +244,7 @@ private static List<HandlerMapping> initFallback(ApplicationContext applicationC
 		catch (IOException ex) {
 			throw new IllegalStateException("Could not load '" + path + "': " + ex.getMessage());
 		}
+
 		String value = props.getProperty(HandlerMapping.class.getName());
 		String[] names = StringUtils.commaDelimitedListToStringArray(value);
 		List<HandlerMapping> result = new ArrayList<>(names.length);