Polish "Fix changelog generator missing directly removed properties"

See gh-45267

Author: wilkinsona

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

@@ -21,7 +21,7 @@
 
 import org.springframework.boot.configurationmetadata.ConfigurationMetadataProperty;
 import org.springframework.boot.configurationmetadata.ConfigurationMetadataRepository;
-import org.springframework.boot.configurationmetadata.Deprecation;
+import org.springframework.boot.configurationmetadata.Deprecation.Level;
 
 /**
  * A changelog containing differences computed from two repositories of configuration
@@ -50,19 +50,14 @@ static List<Difference> computeDifferences(ConfigurationMetadataRepository oldMe
 			String id = oldProperty.getId();
 			seenIds.add(id);
 			ConfigurationMetadataProperty newProperty = newMetadata.getAllProperties().get(id);
-			if (newProperty == null) {
-				differences.add(new Difference(DifferenceType.DELETED, oldProperty, null));
-			}
-			else {
-				Difference difference = Difference.compute(oldProperty, newProperty);
-				if (difference != null) {
-					differences.add(difference);
-				}
+			Difference difference = Difference.compute(oldProperty, newProperty);
+			if (difference != null) {
+				differences.add(difference);
 			}
 		}
 		for (ConfigurationMetadataProperty newProperty : newMetadata.getAllProperties().values()) {
 			if (!seenIds.contains(newProperty.getId())) {
-				if (newProperty.isDeprecated() && newProperty.getDeprecation().getLevel() == Deprecation.Level.ERROR) {
+				if (newProperty.isDeprecated() && newProperty.getDeprecation().getLevel() == Level.ERROR) {
 					differences.add(new Difference(DifferenceType.DELETED, null, newProperty));
 				}
 				else if (!newProperty.isDeprecated()) {

spring-boot-project/spring-boot-tools/spring-boot-configuration-metadata-changelog-generator/src/test/resources/sample-1.0.json

@@ -26,6 +26,15 @@
       "deprecation": {
         "level": "warning"
       }
+    },
+    {
+      "name": "test.delete.error",
+      "type": "java.lang.String",
+      "description": "Test delete error.",
+      "defaultValue": "delete",
+      "deprecation": {
+        "level": "error"
+      }
     }
   ]
 }

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

@@ -40,7 +40,7 @@
       "deprecation": {
         "level": "error",
         "replacement": "test.new.property",
-        "reason": "Removed in Upgrade 10"
+        "reason": "removed in third-party library without deprecation"
       }
     }
   ]

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

@@ -35,5 +35,5 @@ _None_.
 
 | `test.removed.directly`
 | `test.new.property`
-| Removed in Upgrade 10
+| removed in third-party library without deprecation
 |======================