Document properties that were added as deprecated

This commit handles a corner case where we have to add properties in
a release that represents something we mean to remove but that's not
ready to go away just yet.

Those properties are now considered in the changelog, but  marked as
deprecated.

Closes gh-47759

Author: snicoll

configuration-metadata/spring-boot-configuration-metadata-changelog-generator/src/main/java/org/springframework/boot/configurationmetadata/changelog/Changelog.java

@@ -57,12 +57,14 @@ static List<Difference> computeDifferences(ConfigurationMetadataRepository oldMe
 		}
 		for (ConfigurationMetadataProperty newProperty : newMetadata.getAllProperties().values()) {
 			if (!seenIds.contains(newProperty.getId())) {
-				if (newProperty.isDeprecated() && newProperty.getDeprecation().getLevel() == Level.ERROR) {
-					differences.add(new Difference(DifferenceType.DELETED, null, newProperty));
-				}
-				else if (!newProperty.isDeprecated()) {
+				if (!newProperty.isDeprecated()) {
 					differences.add(new Difference(DifferenceType.ADDED, null, newProperty));
 				}
+				else {
+					DifferenceType differenceType = (newProperty.getDeprecation().getLevel() == Level.ERROR)
+							? DifferenceType.DELETED : DifferenceType.ADDED;
+					differences.add(new Difference(differenceType, null, newProperty));
+				}
 			}
 		}
 		return List.copyOf(differences);

configuration-metadata/spring-boot-configuration-metadata-changelog-generator/src/main/java/org/springframework/boot/configurationmetadata/changelog/ChangelogWriter.java

@@ -104,7 +104,10 @@ private void writeAdded(List<Difference> differences) {
 	}
 
 	private void writeAdded(Difference difference) {
-		writeRegularPropertyRow(difference.newProperty());
+		ConfigurationMetadataProperty property = difference.newProperty();
+		writeCell(monospace(property.getId()) + (property.isDeprecated() ? " (deprecated)" : ""));
+		writeCell(monospace(asString(property.getDefaultValue())));
+		writeCell(property.getShortDescription());
 	}
 
 	private void writeRemoved(List<Difference> deleted, List<Difference> deprecated) {
@@ -157,12 +160,6 @@ private void writeTableBreak() {
 		write("|======================%n");
 	}
 
-	private void writeRegularPropertyRow(ConfigurationMetadataProperty property) {
-		writeCell(monospace(property.getId()));
-		writeCell(monospace(asString(property.getDefaultValue())));
-		writeCell(property.getShortDescription());
-	}
-
 	private void writeDeprecatedPropertyRow(ConfigurationMetadataProperty property) {
 		Deprecation deprecation = (property.getDeprecation() != null) ? property.getDeprecation() : new Deprecation();
 		writeCell(monospace(property.getId()));

configuration-metadata/spring-boot-configuration-metadata-changelog-generator/src/test/java/org/springframework/boot/configurationmetadata/changelog/ChangelogTests.java

@@ -39,13 +39,14 @@ void diffContainsDifferencesBetweenLeftAndRightInputs() {
 		assertThat(differences).isNotNull();
 		assertThat(differences.oldVersionNumber()).isEqualTo("1.0");
 		assertThat(differences.newVersionNumber()).isEqualTo("2.0");
-		assertThat(differences.differences()).hasSize(5);
+		assertThat(differences.differences()).hasSize(6);
 		List<Difference> added = differences.differences()
 			.stream()
 			.filter((difference) -> difference.type() == DifferenceType.ADDED)
 			.toList();
-		assertThat(added).hasSize(1);
-		assertProperty(added.get(0).newProperty(), "test.add", String.class, "new");
+		assertThat(added).hasSize(2)
+			.anySatisfy((entry) -> assertProperty(entry.newProperty(), "test.add", String.class, "new"))
+			.anySatisfy((entry) -> assertProperty(entry.newProperty(), "test.add.deprecated", String.class, "test2"));
 		List<Difference> deleted = differences.differences()
 			.stream()
 			.filter((difference) -> difference.type() == DifferenceType.DELETED)

configuration-metadata/spring-boot-configuration-metadata-changelog-generator/src/test/resources/sample-2.0.json

@@ -6,6 +6,16 @@
       "description": "Test add.",
       "defaultValue": "new"
     },
+    {
+      "name": "test.add.deprecated",
+      "type": "java.lang.String",
+      "description": "Test add deprecated.",
+      "defaultValue": "test2",
+      "deprecation": {
+        "replacement": "test.equal",
+        "reason": "Deprecated  in favor of Equal"
+      }
+    },
     {
       "name": "test.equal",
       "type": "java.lang.String",

configuration-metadata/spring-boot-configuration-metadata-changelog-generator/src/test/resources/sample.adoc

@@ -16,6 +16,10 @@ _None_.
 | `test.add`
 | `new`
 | Test add.
+
+| `test.add.deprecated` (deprecated)
+| `test2`
+| Test add deprecated.
 |======================