Merge branch '3.1.x'

Closes gh-37184

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/docker/type/ImageReference.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.buildpack.platform.docker.type;
 
 import java.io.File;
+import java.util.Locale;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -260,7 +261,8 @@ public final class ImageReference {
 				path = path.substring(0, tagSplit) + remainder;
 			}
 		}
-		Assert.isTrue(Regex.PATH.matcher(path).matches(),
+
+		Assert.isTrue(isLowerCase(path) && matchesPathRegex(path),
 				() -> "Unable to parse image reference \"" + value + "\". "
 						+ "Image reference must be in the form '[domainHost:port/][path/]name[:tag][@digest]', "
 						+ "with 'path' and 'name' containing only [a-z0-9][.][_][-]");
@@ -268,6 +270,14 @@ public final class ImageReference {
 		return new ImageReference(name, tag, digest);
 	}
 
+	private static boolean isLowerCase(String path) {
+		return path.toLowerCase(Locale.ENGLISH).equals(path);
+	}
+
+	private static boolean matchesPathRegex(String path) {
+		return Regex.PATH.matcher(path).matches();
+	}
+
 	/**
 	 * Create a new {@link ImageReference} from the given {@link ImageName}.
 	 * @param name the image name

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

@@ -180,6 +180,14 @@ class ImageReferenceTests {
 			.withMessageContaining("Unable to parse image reference");
 	}
 
+	@Test
+	void ofWhenContainsUpperCaseThrowsException() {
+		assertThatIllegalArgumentException()
+			.isThrownBy(() -> ImageReference
+				.of("europe-west1-docker.pkg.dev/aaaaaa-bbbbb-123456/docker-registry/bootBuildImage:0.0.1"))
+			.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");