Use Supplier variants of Assert methods

See gh-12630

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/archive/ArchiveCommand.java

@@ -124,14 +124,14 @@ abstract class ArchiveCommand extends OptionParsingCommand {
 		protected ExitStatus run(OptionSet options) throws Exception {
 			List<?> nonOptionArguments = new ArrayList<Object>(
 					options.nonOptionArguments());
-			Assert.isTrue(nonOptionArguments.size() >= 2, "The name of the resulting "
+			Assert.isTrue(nonOptionArguments.size() >= 2, () -> "The name of the resulting "
 					+ this.type + " and at least one source file must be specified");
 
 			File output = new File((String) nonOptionArguments.remove(0));
 			Assert.isTrue(
 					output.getName().toLowerCase(Locale.ENGLISH)
 							.endsWith("." + this.type),
-					"The output '" + output + "' is not a "
+					() -> "The output '" + output + "' is not a "
 							+ this.type.toUpperCase(Locale.ENGLISH) + " file.");
 			deleteIfExists(output);