Merge branch '2.3.x' into 2.4.x

Closes gh-26702

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/java/org/springframework/boot/buildpack/platform/docker/type/ImageReferenceTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -171,6 +171,14 @@ class ImageReferenceTests {
 				"docker.io/library/ubuntu:bionic@sha256:6e9f67fa63b0323e9a1e587fd71c561ba48a034504fb804fd26fd8800039835d");
 	}
 
+	@Test
+	void ofWhenHasIllegalCharacter() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> ImageReference
+						.of("registry.example.com/example/example-app:1.6.0-dev.2.uncommitted+wip.foo.c75795d"))
+				.withMessageContaining("Unable to parse image reference");
+	}
+
 	@Test
 	void forJarFile() {
 		assertForJarFile("spring-boot.2.0.0.BUILD-SNAPSHOT.jar", "library/spring-boot", "2.0.0.BUILD-SNAPSHOT");