Remove MD5 from RandomValuePropertySource

Before that change, we get 32 random bytes, and then used MD5 on them to
get a hex string. This removes the MD5, we now get 128 bits (output size
 of MD5) of random bytes directly.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/env/RandomValuePropertySource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.env;
 
+import java.util.HexFormat;
 import java.util.OptionalInt;
 import java.util.OptionalLong;
 import java.util.Random;
@@ -31,7 +32,6 @@ import org.springframework.core.env.PropertySource;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.log.LogMessage;
 import org.springframework.util.Assert;
-import org.springframework.util.DigestUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -58,6 +58,7 @@ import org.springframework.util.StringUtils;
  * @author Dave Syer
  * @author Matt Benson
  * @author Madhura Bhave
+ * @author Moritz Halbritter
  * @since 1.0.0
  */
 public class RandomValuePropertySource extends PropertySource<Random> {
@@ -136,9 +137,9 @@ public class RandomValuePropertySource extends PropertySource<Random> {
 	}
 
 	private Object getRandomBytes() {
-		byte[] bytes = new byte[32];
+		byte[] bytes = new byte[16];
 		getSource().nextBytes(bytes);
-		return DigestUtils.md5DigestAsHex(bytes);
+		return HexFormat.of().withLowerCase().formatHex(bytes);
 	}
 
 	public static void addToEnvironment(ConfigurableEnvironment environment) {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/env/RandomValuePropertySourceTests.java

@@ -37,6 +37,7 @@ import static org.mockito.Mockito.spy;
  *
  * @author Dave Syer
  * @author Matt Benson
+ * @author Moritz Halbritter
  */
 class RandomValuePropertySourceTests {
 
@@ -192,4 +193,9 @@ class RandomValuePropertySourceTests {
 				RandomValuePropertySource.RANDOM_PROPERTY_SOURCE_NAME, "mockProperties");
 	}
 
+	@Test
+	void randomStringIs32CharsLong() {
+		assertThat(this.source.getProperty("random.string")).asString().hasSize(32);
+	}
+
 }