[prone] Add RedundantStringConversion

Author: Vincent Potucek

build.gradle

@@ -20,10 +20,11 @@ plugins {
 
 description = "Spring Boot Build"
 
-defaultTasks 'build'
+defaultTasks "build"
 
 allprojects {
 	group = "org.springframework.boot"
+	apply from: rootProject.file("gradle/error-prone.gradle")
 }
 
 subprojects {

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

@@ -55,7 +55,7 @@ AnsiString append(String text, Code... codes) {
 		for (Code code : codes) {
 			ansi = applyCode(ansi, code);
 		}
-		this.value.append(ansi.a(text).reset().toString());
+		this.value.append(ansi.a(text).reset());
 		return this;
 	}
 

core/spring-boot-autoconfigure-processor/src/main/java/org/springframework/boot/autoconfigureprocessor/Elements.java

@@ -36,7 +36,7 @@ static String getQualifiedName(Element element) {
 			TypeElement enclosingElement = getEnclosingTypeElement(element.asType());
 			if (enclosingElement != null) {
 				return getQualifiedName(enclosingElement) + "$"
-						+ ((DeclaredType) element.asType()).asElement().getSimpleName().toString();
+						+ ((DeclaredType) element.asType()).asElement().getSimpleName();
 			}
 			if (element instanceof TypeElement typeElement) {
 				return typeElement.getQualifiedName().toString();

core/spring-boot/src/main/java/org/springframework/boot/context/properties/source/FilteredConfigurationPropertiesSource.java

@@ -73,7 +73,7 @@ protected Predicate<ConfigurationPropertyName> getFilter() {
 
 	@Override
 	public String toString() {
-		return this.source.toString() + " (filtered)";
+		return this.source + " (filtered)";
 	}
 
 }

gradle/error-prone.gradle

@@ -0,0 +1,21 @@
+import static java.lang.System.getenv
+
+apply plugin: "net.ltgt.errorprone"
+
+dependencies {
+	errorprone("com.google.errorprone:error_prone_core:2.42.0")
+	errorprone("tech.picnic.error-prone-support:error-prone-contrib:0.25.0")
+}
+
+tasks.withType(JavaCompile).configureEach {
+	options.errorprone {
+		disableAllChecks = true
+		error("RedundantStringConversion")
+		if (!getenv().containsKey("CI") && getenv("IN_PLACE")?.toBoolean()) {
+			errorproneArgs.addAll(
+					"-XepPatchLocation:IN_PLACE",
+					"-XepPatchChecks:RedundantStringConversion"
+					)
+		}
+	}
+}

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/management/PlainTextThreadDumpFormatter.java

@@ -77,7 +77,7 @@ private List<MonitorInfo> lockedMonitorsForDepth(MonitorInfo[] lockedMonitors, i
 
 	private void writeStackTraceElement(PrintWriter writer, StackTraceElement element, ThreadInfo info,
 			List<MonitorInfo> lockedMonitors, boolean firstElement) {
-		writer.printf("\tat %s%n", element.toString());
+		writer.printf("\tat %s%n", element);
 		LockInfo lockInfo = info.getLockInfo();
 		if (firstElement && lockInfo != null) {
 			if (element.getClassName().equals(Object.class.getName()) && element.getMethodName().equals("wait")) {