Use the platform-specific line separator

Closes gh-11674

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/diagnostics/analyzer/InvalidConfigurationPropertyValueFailureAnalyzer.java

@@ -94,7 +94,8 @@ class InvalidConfigurationPropertyValueFailureAnalyzer
 	private void appendReason(StringBuilder message,
 			InvalidConfigurationPropertyValueException cause) {
 		if (StringUtils.hasText(cause.getReason())) {
-			message.append(" Validation failed for the following reason:\n\n");
+			message.append(String.format(" Validation failed for the following "
+					+ "reason:%n%n"));
 			message.append(cause.getReason());
 		}
 		else {
@@ -114,7 +115,7 @@ class InvalidConfigurationPropertyValueFailureAnalyzer
 				message.append("\t- In '" + other.getPropertySource() + "'");
 				message.append(" with the value '" + other.getValue() + "'");
 				other.appendOrigin(message);
-				message.append(".\n");
+				message.append(String.format(".%n"));
 			}
 		}
 	}