Update Bomr to treat CalVer versions as newer than release train versions

Closes gh-23451

buildSrc/src/main/java/org/springframework/boot/build/bom/bomr/version/ArtifactVersionDependencyVersion.java

@@ -80,7 +80,7 @@ class ArtifactVersionDependencyVersion extends AbstractDependencyVersion {
 		return this.artifactVersion.toString();
 	}
 
-	private Optional<ArtifactVersionDependencyVersion> extractArtifactVersionDependencyVersion(
+	protected Optional<ArtifactVersionDependencyVersion> extractArtifactVersionDependencyVersion(
 			DependencyVersion other) {
 		ArtifactVersionDependencyVersion artifactVersion = null;
 		if (other instanceof ArtifactVersionDependencyVersion) {

buildSrc/src/main/java/org/springframework/boot/build/bom/bomr/version/CalendarVersionDependencyVersion.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2012-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.build.bom.bomr.version;
+
+import java.util.regex.Pattern;
+
+import org.apache.maven.artifact.versioning.ArtifactVersion;
+import org.apache.maven.artifact.versioning.ComparableVersion;
+import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
+
+/**
+ * A specialization of {@link ArtifactVersionDependencyVersion} for calendar versions.
+ * Calendar versions are always considered to be newer than
+ * {@link ReleaseTrainDependencyVersion release train versions}.
+ *
+ * @author Andy Wilkinson
+ */
+class CalendarVersionDependencyVersion extends ArtifactVersionDependencyVersion {
+
+	private static final Pattern CALENDAR_VERSION_PATTERN = Pattern.compile("\\d{4}\\.\\d+\\.\\d+(-.+)?");
+
+	protected CalendarVersionDependencyVersion(ArtifactVersion artifactVersion) {
+		super(artifactVersion);
+	}
+
+	protected CalendarVersionDependencyVersion(ArtifactVersion artifactVersion, ComparableVersion comparableVersion) {
+		super(artifactVersion, comparableVersion);
+	}
+
+	@Override
+	public boolean isNewerThan(DependencyVersion other) {
+		if (other instanceof ReleaseTrainDependencyVersion) {
+			return true;
+		}
+		return super.isNewerThan(other);
+	}
+
+	static CalendarVersionDependencyVersion parse(String version) {
+		if (!CALENDAR_VERSION_PATTERN.matcher(version).matches()) {
+			return null;
+		}
+		ArtifactVersion artifactVersion = new DefaultArtifactVersion(version);
+		if (artifactVersion.getQualifier() != null && artifactVersion.getQualifier().equals(version)) {
+			return null;
+		}
+		return new CalendarVersionDependencyVersion(artifactVersion);
+	}
+
+}

buildSrc/src/main/java/org/springframework/boot/build/bom/bomr/version/DependencyVersion.java

@@ -53,10 +53,10 @@ public interface DependencyVersion extends Comparable<DependencyVersion> {
 	boolean isSameMinorAndNewerThan(DependencyVersion other);
 
 	static DependencyVersion parse(String version) {
-		List<Function<String, DependencyVersion>> parsers = Arrays.asList(ArtifactVersionDependencyVersion::parse,
-				ReleaseTrainDependencyVersion::parse, NumericQualifierDependencyVersion::parse,
-				CombinedPatchAndQualifierDependencyVersion::parse, LeadingZeroesDependencyVersion::parse,
-				UnstructuredDependencyVersion::parse);
+		List<Function<String, DependencyVersion>> parsers = Arrays.asList(CalendarVersionDependencyVersion::parse,
+				ArtifactVersionDependencyVersion::parse, ReleaseTrainDependencyVersion::parse,
+				NumericQualifierDependencyVersion::parse, CombinedPatchAndQualifierDependencyVersion::parse,
+				LeadingZeroesDependencyVersion::parse, UnstructuredDependencyVersion::parse);
 		for (Function<String, DependencyVersion> parser : parsers) {
 			DependencyVersion result = parser.apply(version);
 			if (result != null) {

buildSrc/src/main/java/org/springframework/boot/build/bom/bomr/version/ReleaseTrainDependencyVersion.java

@@ -64,6 +64,9 @@ final class ReleaseTrainDependencyVersion implements DependencyVersion {
 
 	@Override
 	public boolean isNewerThan(DependencyVersion other) {
+		if (other instanceof CalendarVersionDependencyVersion) {
+			return false;
+		}
 		if (!(other instanceof ReleaseTrainDependencyVersion)) {
 			return true;
 		}
@@ -78,6 +81,9 @@ final class ReleaseTrainDependencyVersion implements DependencyVersion {
 
 	@Override
 	public boolean isSameMinorAndNewerThan(DependencyVersion other) {
+		if (other instanceof CalendarVersionDependencyVersion) {
+			return false;
+		}
 		if (!(other instanceof ReleaseTrainDependencyVersion)) {
 			return true;
 		}