Merge pull request #19540 from jason-liu475

* pr/19540:
  Polish "Make equality checks defensive to null reference"
  Make equality checks defensive to null reference

Closes gh-19540

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/util/ResourceUtils.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -102,7 +102,7 @@ public abstract class ResourceUtils {
 		List<String> result = new ArrayList<>();
 		for (Resource resource : resources) {
 			if (resource.exists()) {
-				if (resource.getURI().getScheme().equals("file") && resource.getFile().isDirectory()) {
+				if ("file".equals(resource.getURI().getScheme()) && resource.getFile().isDirectory()) {
 					result.addAll(getChildFiles(resource));
 					continue;
 				}
@@ -124,7 +124,7 @@ public abstract class ResourceUtils {
 	}
 
 	private static String absolutePath(Resource resource) throws IOException {
-		if (!resource.getURI().getScheme().equals("file")) {
+		if (!"file".equals(resource.getURI().getScheme())) {
 			return resource.getURL().toExternalForm();
 		}
 		return resource.getFile().getAbsoluteFile().toURI().toString();

spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/restdocs/RestDocsWebTestClientBuilderCustomizer.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -61,7 +61,7 @@ class RestDocsWebTestClientBuilderCustomizer implements WebTestClientBuilderCust
 		if (port == null) {
 			return true;
 		}
-		return (scheme.equals("http") && port == 80) || (scheme.equals("https") && port == 443);
+		return ("http".equals(scheme) && port == 80) || ("https".equals(scheme) && port == 443);
 	}
 
 }