Add since to deprecations in config metadata JSON files

Add the `since` field to all deprecated properties in all
additional-spring-configuration-metadata.json files in the project.

Add to the CheckAdditionalSpringConfigurationMetadata build task to
ensure that all deprecated properties have a non-empty `since` field.

Author: scottfrederick

buildSrc/src/main/java/org/springframework/boot/build/context/properties/CheckAdditionalSpringConfigurationMetadata.java

@@ -28,8 +28,6 @@
 import java.util.List;
 import java.util.Map;
 
-import com.fasterxml.jackson.core.JsonParseException;
-import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.gradle.api.file.FileTree;
 import org.gradle.api.file.RegularFileProperty;
@@ -65,7 +63,7 @@ public FileTree getSource() {
 	}
 
 	@TaskAction
-	void check() throws JsonParseException, IOException {
+	void check() throws IOException {
 		Report report = createReport();
 		File reportFile = getReportLocation().get().getAsFile();
 		Files.write(reportFile.toPath(), report, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
@@ -76,21 +74,22 @@ void check() throws JsonParseException, IOException {
 	}
 
 	@SuppressWarnings("unchecked")
-	private Report createReport() throws IOException, JsonParseException, JsonMappingException {
+	private Report createReport() throws IOException {
 		ObjectMapper objectMapper = new ObjectMapper();
 		Report report = new Report();
 		for (File file : getSource().getFiles()) {
 			Analysis analysis = report.analysis(this.projectDir.toPath().relativize(file.toPath()));
 			Map<String, Object> json = objectMapper.readValue(file, Map.class);
-			check("groups", json, analysis);
-			check("properties", json, analysis);
-			check("hints", json, analysis);
+			checkSorting("groups", json, analysis);
+			checkSorting("properties", json, analysis);
+			checkSorting("hints", json, analysis);
+			checkPropertyDeprecationSince(json, analysis);
 		}
 		return report;
 	}
 
 	@SuppressWarnings("unchecked")
-	private void check(String key, Map<String, Object> json, Analysis analysis) {
+	private void checkSorting(String key, Map<String, Object> json, Analysis analysis) {
 		List<Map<String, Object>> groups = (List<Map<String, Object>>) json.getOrDefault(key, Collections.emptyList());
 		List<String> names = groups.stream().map((group) -> (String) group.get("name")).toList();
 		List<String> sortedNames = sortedCopy(names);
@@ -110,6 +109,18 @@ private List<String> sortedCopy(Collection<String> original) {
 		return copy;
 	}
 
+	@SuppressWarnings("unchecked")
+	private void checkPropertyDeprecationSince(Map<String, Object> json, Analysis analysis) {
+		List<Map<String, Object>> properties = (List<Map<String, Object>>) json.get("properties");
+		properties.stream().filter((property) -> property.containsKey("deprecation")).forEach((property) -> {
+			Map<String, Object> deprecation = (Map<String, Object>) property.get("deprecation");
+			if (!deprecation.containsKey("since")) {
+				analysis.problems.add("Property with name '" + property.get("name")
+						+ "' contains 'deprecation' without 'since' attribute");
+			}
+		});
+	}
+
 	private static final class Report implements Iterable<String> {
 
 		private final List<Analysis> analyses = new ArrayList<>();