Replacing StringBuffer with lock-free StringBuilder

Closes gh-5727

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

@@ -74,7 +74,7 @@ class OnBeanCondition extends SpringBootCondition implements ConfigurationCondit
 	@Override
 	public ConditionOutcome getMatchOutcome(ConditionContext context,
 			AnnotatedTypeMetadata metadata) {
-		StringBuffer matchMessage = new StringBuffer();
+		StringBuilder matchMessage = new StringBuilder();
 		if (metadata.isAnnotated(ConditionalOnBean.class.getName())) {
 			BeanSearchSpec spec = new BeanSearchSpec(context, metadata,
 					ConditionalOnBean.class);
@@ -83,8 +83,8 @@ class OnBeanCondition extends SpringBootCondition implements ConfigurationCondit
 				return ConditionOutcome
 						.noMatch("@ConditionalOnBean " + spec + " found no beans");
 			}
-			matchMessage.append(
-					"@ConditionalOnBean " + spec + " found the following " + matching);
+			matchMessage.append("@ConditionalOnBean ").append(spec)
+					.append(" found the following ").append(matching);
 		}
 		if (metadata.isAnnotated(ConditionalOnSingleCandidate.class.getName())) {
 			BeanSearchSpec spec = new SingleCandidateBeanSearchSpec(context, metadata,
@@ -99,8 +99,8 @@ class OnBeanCondition extends SpringBootCondition implements ConfigurationCondit
 						+ " found no primary candidate amongst the" + " following "
 						+ matching);
 			}
-			matchMessage.append("@ConditionalOnSingleCandidate " + spec + " found "
-					+ "a primary candidate amongst the following " + matching);
+			matchMessage.append("@ConditionalOnSingleCandidate ").append(spec)
+					.append(" found a primary candidate amongst the following ").append(matching);
 		}
 		if (metadata.isAnnotated(ConditionalOnMissingBean.class.getName())) {
 			BeanSearchSpec spec = new BeanSearchSpec(context, metadata,
@@ -111,7 +111,8 @@ class OnBeanCondition extends SpringBootCondition implements ConfigurationCondit
 						+ " found the following " + matching);
 			}
 			matchMessage.append(matchMessage.length() == 0 ? "" : " ");
-			matchMessage.append("@ConditionalOnMissingBean " + spec + " found no beans");
+			matchMessage.append("@ConditionalOnMissingBean ").append(spec)
+					.append(" found no beans");
 		}
 		return ConditionOutcome.match(matchMessage.toString());
 	}

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

@@ -44,7 +44,7 @@ class OnClassCondition extends SpringBootCondition {
 	public ConditionOutcome getMatchOutcome(ConditionContext context,
 			AnnotatedTypeMetadata metadata) {
 
-		StringBuffer matchMessage = new StringBuffer();
+		StringBuilder matchMessage = new StringBuilder();
 
 		MultiValueMap<String, Object> onClasses = getAttributes(metadata,
 				ConditionalOnClass.class);
@@ -56,8 +56,8 @@ class OnClassCondition extends SpringBootCondition {
 						.noMatch("required @ConditionalOnClass classes not found: "
 								+ StringUtils.collectionToCommaDelimitedString(missing));
 			}
-			matchMessage.append("@ConditionalOnClass classes found: "
-					+ StringUtils.collectionToCommaDelimitedString(
+			matchMessage.append("@ConditionalOnClass classes found: ")
+					.append(StringUtils.collectionToCommaDelimitedString(
 							getMatchingClasses(onClasses, MatchType.PRESENT, context)));
 		}
 
@@ -72,9 +72,9 @@ class OnClassCondition extends SpringBootCondition {
 								+ StringUtils.collectionToCommaDelimitedString(present));
 			}
 			matchMessage.append(matchMessage.length() == 0 ? "" : " ");
-			matchMessage.append("@ConditionalOnMissing classes not found: "
-					+ StringUtils.collectionToCommaDelimitedString(getMatchingClasses(
-							onMissingClasses, MatchType.MISSING, context)));
+			matchMessage.append("@ConditionalOnMissing classes not found: ")
+					.append(StringUtils.collectionToCommaDelimitedString(getMatchingClasses(
+					onMissingClasses, MatchType.MISSING, context)));
 		}
 
 		return ConditionOutcome.match(matchMessage.toString());

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

@@ -83,8 +83,8 @@ class OnPropertyCondition extends SpringBootCondition {
 
 		StringBuilder message = new StringBuilder("@ConditionalOnProperty ");
 		if (!missingProperties.isEmpty()) {
-			message.append("missing required properties "
-					+ expandNames(prefix, missingProperties) + " ");
+			message.append("missing required properties ").append(expandNames(prefix, missingProperties))
+					.append(" ");
 		}
 		if (!nonMatchingProperties.isEmpty()) {
 			String expected = StringUtils.hasLength(havingValue) ? havingValue : "!false";
@@ -113,7 +113,7 @@ class OnPropertyCondition extends SpringBootCondition {
 	}
 
 	private String expandNames(String prefix, List<String> names) {
-		StringBuffer expanded = new StringBuffer();
+		StringBuilder expanded = new StringBuilder();
 		for (String name : names) {
 			expanded.append(expanded.length() == 0 ? "" : ", ");
 			expanded.append(prefix);

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/shell/CommandCompleter.java

@@ -127,7 +127,7 @@ public class CommandCompleter extends StringsCompleter {
 		private final String usage;
 
 		OptionHelpLine(OptionHelp optionHelp) {
-			StringBuffer options = new StringBuffer();
+			StringBuilder options = new StringBuilder();
 			for (String option : optionHelp.getOptions()) {
 				options.append(options.length() == 0 ? "" : ", ");
 				options.append(option);

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/livereload/ConnectionInputStream.java

@@ -44,7 +44,7 @@ class ConnectionInputStream extends FilterInputStream {
 	 */
 	public String readHeader() throws IOException {
 		byte[] buffer = new byte[BUFFER_SIZE];
-		StringBuffer content = new StringBuffer(BUFFER_SIZE);
+		StringBuilder content = new StringBuilder(BUFFER_SIZE);
 		while (content.indexOf(HEADER_END) == -1) {
 			int amountRead = checkedRead(buffer, 0, BUFFER_SIZE);
 			content.append(new String(buffer, 0, amountRead));

spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractRunMojo.java

@@ -401,7 +401,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	}
 
 	private void logArguments(String message, String[] args) {
-		StringBuffer sb = new StringBuffer(message);
+		StringBuilder sb = new StringBuilder(message);
 		for (String arg : args) {
 			sb.append(arg).append(" ");
 		}