Adapt to deprecation of StringUtils.isEmpty(Object)

See gh-23774

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/ConditionMessage.java

@@ -296,11 +296,11 @@ public final class ConditionMessage {
 		 * @return a built {@link ConditionMessage}
 		 */
 		public ConditionMessage because(String reason) {
-			if (StringUtils.isEmpty(reason)) {
-				return new ConditionMessage(ConditionMessage.this, this.condition);
+			if (StringUtils.hasLength(reason)) {
+				return new ConditionMessage(ConditionMessage.this,
+						StringUtils.hasLength(this.condition) ? this.condition + " " + reason : reason);
 			}
-			return new ConditionMessage(ConditionMessage.this,
-					StringUtils.isEmpty(this.condition) ? reason : this.condition + " " + reason);
+			return new ConditionMessage(ConditionMessage.this, this.condition);
 		}
 
 	}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/domain/EntityScanPackages.java

@@ -140,7 +140,7 @@ public class EntityScanPackages {
 			}
 			if (packagesToScan.isEmpty()) {
 				String packageName = ClassUtils.getPackageName(metadata.getClassName());
-				Assert.state(!StringUtils.isEmpty(packageName), "@EntityScan cannot be used with the default package");
+				Assert.state(StringUtils.hasLength(packageName), "@EntityScan cannot be used with the default package");
 				return Collections.singleton(packageName);
 			}
 			return packagesToScan;

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/util/TestPropertyValues.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.
@@ -277,10 +277,10 @@ public final class TestPropertyValues {
 		}
 
 		private static Pair of(String name, String value) {
-			if (StringUtils.isEmpty(name) && StringUtils.isEmpty(value)) {
-				return null;
+			if (StringUtils.hasLength(name) || StringUtils.hasLength(value)) {
+				return new Pair(name, value);
 			}
-			return new Pair(name, value);
+			return null;
 		}
 
 	}
@@ -309,7 +309,7 @@ public final class TestPropertyValues {
 
 		private String setOrClear(String name, String value) {
 			Assert.notNull(name, "Name must not be null");
-			if (StringUtils.isEmpty(value)) {
+			if (!StringUtils.hasLength(value)) {
 				return (String) System.getProperties().remove(name);
 			}
 			return (String) System.getProperties().setProperty(name, value);

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/docker/transport/DockerEngineException.java

@@ -87,10 +87,10 @@ public class DockerEngineException extends RuntimeException {
 		Assert.notNull(uri, "URI must not be null");
 		StringBuilder message = new StringBuilder(
 				"Docker API call to '" + host + uri + "' failed with status code " + statusCode);
-		if (!StringUtils.isEmpty(reasonPhrase)) {
+		if (StringUtils.hasLength(reasonPhrase)) {
 			message.append(" \"").append(reasonPhrase).append("\"");
 		}
-		if (responseMessage != null && !StringUtils.isEmpty(responseMessage.getMessage())) {
+		if (responseMessage != null && StringUtils.hasLength(responseMessage.getMessage())) {
 			message.append(" and message \"").append(responseMessage.getMessage()).append("\"");
 		}
 		if (errors != null && !errors.isEmpty()) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/Log4J2LoggingSystem.java

@@ -258,7 +258,7 @@ public class Log4J2LoggingSystem extends Slf4JLoggingSystem {
 	}
 
 	private String getSubName(String name) {
-		if (StringUtils.isEmpty(name)) {
+		if (!StringUtils.hasLength(name)) {
 			return null;
 		}
 		int nested = name.lastIndexOf('$');

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/context/WebServerPortFileWriter.java

@@ -105,7 +105,7 @@ public class WebServerPortFileWriter implements ApplicationListener<WebServerIni
 	 */
 	protected File getPortFile(ApplicationContext applicationContext) {
 		String namespace = getServerNamespace(applicationContext);
-		if (StringUtils.isEmpty(namespace)) {
+		if (!StringUtils.hasLength(namespace)) {
 			return this.file;
 		}
 		String name = this.file.getName();

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/netty/CompressionCustomizer.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.
@@ -71,7 +71,7 @@ final class CompressionCustomizer implements NettyServerCustomizer {
 				.collect(Collectors.toList());
 		return (request, response) -> {
 			String contentType = response.responseHeaders().get(HttpHeaderNames.CONTENT_TYPE);
-			if (StringUtils.isEmpty(contentType)) {
+			if (!StringUtils.hasLength(contentType)) {
 				return false;
 			}
 			try {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServer.java

@@ -123,7 +123,7 @@ public class UndertowServletWebServer extends UndertowWebServer {
 	@Override
 	protected HttpHandler createHttpHandler() {
 		HttpHandler handler = super.createHttpHandler();
-		if (!StringUtils.isEmpty(this.contextPath)) {
+		if (StringUtils.hasLength(this.contextPath)) {
 			handler = Handlers.path().addPrefixPath(this.contextPath, handler);
 		}
 		return handler;

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/server/SslConfigurationValidator.java

@@ -34,7 +34,7 @@ public final class SslConfigurationValidator {
 	}
 
 	public static void validateKeyAlias(KeyStore keyStore, String keyAlias) {
-		if (!StringUtils.isEmpty(keyAlias)) {
+		if (StringUtils.hasLength(keyAlias)) {
 			try {
 				Assert.state(keyStore.containsAlias(keyAlias),
 						() -> String.format("Keystore does not contain specified alias '%s'", keyAlias));

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/error/DefaultErrorAttributes.java

@@ -32,6 +32,7 @@ import org.springframework.boot.web.error.ErrorAttributeOptions.Include;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
 import org.springframework.http.HttpStatus;
+import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.validation.BindingResult;
 import org.springframework.validation.ObjectError;
@@ -199,10 +200,10 @@ public class DefaultErrorAttributes implements ErrorAttributes, HandlerException
 	 */
 	protected String getMessage(WebRequest webRequest, Throwable error) {
 		Object message = getAttribute(webRequest, RequestDispatcher.ERROR_MESSAGE);
-		if (!StringUtils.isEmpty(message)) {
+		if (!ObjectUtils.isEmpty(message)) {
 			return message.toString();
 		}
-		if (error != null && !StringUtils.isEmpty(error.getMessage())) {
+		if (error != null && StringUtils.hasLength(error.getMessage())) {
 			return error.getMessage();
 		}
 		return "No message available";