Polish "Document properties whose default values have changed"

This commit adds a new section in the Configuration Changelog to
indicate properties whose default values have changed.

See gh-48962

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

@@ -68,8 +68,8 @@ class ChangelogWriter implements AutoCloseable {
 		String newVersionNumber = changelog.newVersionNumber();
 		Map<DifferenceType, List<Difference>> differencesByType = collateByType(changelog);
 		write("Configuration property changes between `%s` and `%s`%n", oldVersionNumber, newVersionNumber);
-		write("%n%n%n== Default Value Changed in %s%n%n", newVersionNumber);
-		writeDefaultValueChanged(differencesByType.get(DifferenceType.DEFAULT_VALUE_CHANGED));
+		write("%n%n%n== Default Changed in %s%n%n", newVersionNumber);
+		writeDefaultChanged(differencesByType.get(DifferenceType.DEFAULT_CHANGED));
 		write("%n%n%n== Deprecated in %s%n%n", newVersionNumber);
 		writeDeprecated(differencesByType.get(DifferenceType.DEPRECATED));
 		write("%n%n%n== Added in %s%n%n", newVersionNumber);
@@ -100,12 +100,12 @@ class ChangelogWriter implements AutoCloseable {
 		writeDeprecatedPropertyRow(difference.newProperty());
 	}
 
-	private void writeDefaultValueChanged(List<Difference> differences) {
+	private void writeDefaultChanged(List<Difference> differences) {
 		List<Difference> rows = sortProperties(differences, Difference::newProperty);
-		writeTable("| Key | Old Default | New Default", rows, this::writeDefaultValueChanged);
+		writeTable("| Key | Old Default | New Default", rows, this::writeDefaultChanged);
 	}
 
-	private void writeDefaultValueChanged(Difference difference) {
+	private void writeDefaultChanged(Difference difference) {
 		writeCell(monospace(difference.newProperty().getId()));
 		writeCell(monospace(asString(difference.oldProperty().getDefaultValue())));
 		writeCell(monospace(asString(difference.newProperty().getDefaultValue())));

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

@@ -52,7 +52,7 @@ record Difference(DifferenceType type, ConfigurationMetadataProperty oldProperty
 			return new Difference(DifferenceType.DELETED, oldProperty, newProperty);
 		}
 		if (!Objects.equals(oldProperty.getDefaultValue(), newProperty.getDefaultValue())) {
-			return new Difference(DifferenceType.DEFAULT_VALUE_CHANGED, oldProperty, newProperty);
+			return new Difference(DifferenceType.DEFAULT_CHANGED, oldProperty, newProperty);
 		}
 		return null;
 	}

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

@@ -40,8 +40,9 @@ enum DifferenceType {
 	DELETED,
 
 	/**
-	 * The entry's default value has been changed.
+	 * The entry's default value has changed. The entry exists in both the previous and
+	 * current versions, but its default value is different.
 	 */
-	DEFAULT_VALUE_CHANGED
+	DEFAULT_CHANGED
 
 }

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

@@ -65,19 +65,20 @@ class ChangelogTests {
 		assertThat(deprecated).hasSize(1);
 		assertProperty(deprecated.get(0).oldProperty(), "test.deprecate", String.class, "wrong");
 		assertProperty(deprecated.get(0).newProperty(), "test.deprecate", String.class, "wrong");
-		List<Difference> defaultValueChanged = differences.differences()
+		List<Difference> defaultChanged = differences.differences()
 			.stream()
-			.filter((difference) -> difference.type() == DifferenceType.DEFAULT_VALUE_CHANGED)
+			.filter((difference) -> difference.type() == DifferenceType.DEFAULT_CHANGED)
 			.toList();
-		assertThat(defaultValueChanged).hasSize(2)
-			.anySatisfy((entry) -> assertProperty(entry.newProperty(), "test.default.change", String.class, "new"))
-			.anySatisfy((entry) -> assertThat(entry.newProperty().getId()).isEqualTo("test.array.change"));
+		assertThat(defaultChanged).hasSize(2)
+			.anySatisfy((entry) -> assertProperty(entry.newProperty(), "test.default.array.change", String[].class,
+					new String[] { "b", "a" }))
+			.anySatisfy((entry) -> assertProperty(entry.newProperty(), "test.default.change", String.class, "new"));
 	}
 
 	private void assertProperty(ConfigurationMetadataProperty property, String id, Class<?> type, Object defaultValue) {
 		assertThat(property).isNotNull();
 		assertThat(property.getId()).isEqualTo(id);
-		assertThat(property.getType()).isEqualTo(type.getName());
+		assertThat(property.getType()).isEqualTo(type.getCanonicalName());
 		assertThat(property.getDefaultValue()).isEqualTo(defaultValue);
 	}
 

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

@@ -12,6 +12,12 @@
       "description": "Test default value change.",
       "defaultValue": "old"
     },
+    {
+      "name": "test.default.array.change",
+      "type": "java.lang.String[]",
+      "description": "Test default array value change.",
+      "defaultValue": ["a", "b"]
+    },
     {
       "name": "test.replace",
       "type": "java.lang.String",
@@ -47,12 +53,6 @@
       "deprecation": {
         "level": "error"
       }
-    },
-    {
-      "name": "test.array.change",
-      "type": "java.lang.String[]",
-      "description": "Test array default value change.",
-      "defaultValue": ["a", "b"]
     }
   ]
-}
+}

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

@@ -12,6 +12,12 @@
       "description": "Test default value change.",
       "defaultValue": "new"
     },
+    {
+      "name": "test.default.array.change",
+      "type": "java.lang.String[]",
+      "description": "Test default array value change.",
+      "defaultValue": ["b", "a"]
+    },
     {
       "name": "test.replace",
       "type": "java.lang.String",
@@ -66,12 +72,6 @@
         "replacement": "test.new.property",
         "reason": "removed in third-party library without deprecation"
       }
-    },
-    {
-      "name": "test.array.change",
-      "type": "java.lang.String[]",
-      "description": "Test array default value change.",
-      "defaultValue": ["a", "b", "c"]
     }
   ]
 }

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

@@ -2,14 +2,14 @@ Configuration property changes between `1.0` and `2.0`
 
 
 
-== Default Value Changed in 2.0
+== Default Changed in 2.0
 
 |======================
 | Key | Old Default | New Default
 
-| `test.array.change`
+| `test.default.array.change`
 | `a, b`
-| `a, b, c`
+| `b, a`
 
 | `test.default.change`
 | `old`