Nullability refinements

(cherry picked from commit f31933e6)

spring-web/src/main/java/org/springframework/http/MediaTypeFactory.java

 /*
- * 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.
@@ -28,6 +28,7 @@ import java.util.Optional;
 
 import org.springframework.core.io.Resource;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
@@ -65,6 +66,7 @@ public final class MediaTypeFactory {
 	 */
 	private static MultiValueMap<String, MediaType> parseMimeTypes() {
 		InputStream is = MediaTypeFactory.class.getResourceAsStream(MIME_TYPES_FILE_NAME);
+		Assert.state(is != null, MIME_TYPES_FILE_NAME + " not found in classpath");
 		try (BufferedReader reader = new BufferedReader(new InputStreamReader(is, StandardCharsets.US_ASCII))) {
 			MultiValueMap<String, MediaType> result = new LinkedMultiValueMap<>();
 			String line;
@@ -82,7 +84,7 @@ public final class MediaTypeFactory {
 			return result;
 		}
 		catch (IOException ex) {
-			throw new IllegalStateException("Could not load '" + MIME_TYPES_FILE_NAME + "'", ex);
+			throw new IllegalStateException("Could not read " + MIME_TYPES_FILE_NAME, ex);
 		}
 	}
 

spring-web/src/main/java/org/springframework/web/method/HandlerTypePredicate.java

 /*
- * Copyright 2002-2018 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.
@@ -26,6 +26,7 @@ import java.util.Set;
 import java.util.function.Predicate;
 
 import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
@@ -69,7 +70,7 @@ public final class HandlerTypePredicate implements Predicate<Class<?>> {
 
 
 	@Override
-	public boolean test(Class<?> controllerType) {
+	public boolean test(@Nullable Class<?> controllerType) {
 		if (!hasSelectors()) {
 			return true;
 		}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java

 /*
- * 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.
@@ -718,7 +718,7 @@ public class MvcUriComponentsBuilder {
 
 		@Override
 		@Nullable
-		public Object intercept(Object obj, Method method, Object[] args, @Nullable MethodProxy proxy) {
+		public Object intercept(@Nullable Object obj, Method method, Object[] args, @Nullable MethodProxy proxy) {
 			if (method.getName().equals("getControllerType")) {
 				return this.controllerType;
 			}