Drop unnecessary Collections.unmodifiableSet

See gh-33987

Author: krzyk

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/DefaultLaunchScript.java

@@ -44,8 +44,7 @@ public class DefaultLaunchScript implements LaunchScript {
 
 	private static final Pattern PLACEHOLDER_PATTERN = Pattern.compile("\\{\\{(\\w+)(:.*?)?\\}\\}(?!\\})");
 
-	private static final Set<String> FILE_PATH_KEYS = Collections
-			.unmodifiableSet(Collections.singleton("inlinedConfScript"));
+	private static final Set<String> FILE_PATH_KEYS = Collections.singleton("inlinedConfScript");
 
 	private final String content;