allow query and finder methods to return Optional

required by Jakarta Data spec

Author: gavinking

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/annotation/AbstractQueryMethod.java

@@ -331,7 +331,7 @@ static void closingBrace(StringBuilder declaration) {
 		return returnTypeName;
 	}
 
-	private void unwrapQuery(StringBuilder declaration, boolean unwrapped) {
+	void unwrapQuery(StringBuilder declaration, boolean unwrapped) {
 		if ( !unwrapped ) {
 			declaration
 					.append("\n\t\t\t.unwrap(")

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/annotation/AnnotationMetaEntity.java

@@ -630,6 +630,7 @@ private static boolean isLegalRawResultType(String containerTypeName) {
 
 	private static boolean isLegalGenericResultType(String containerTypeName) {
 		return containerTypeName.equals(Constants.LIST)
+			|| containerTypeName.equals(Constants.OPTIONAL)
 			|| containerTypeName.equals(Constants.TYPED_QUERY)
 			|| containerTypeName.equals(Constants.HIB_QUERY)
 			|| containerTypeName.equals(Constants.HIB_SELECTION_QUERY);

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/annotation/CriteriaFinderMethod.java

@@ -128,6 +128,12 @@ else if ( isOrderParam(paramType) && !isJakartaSortParam(paramType) ) {
 			declaration
 					.append(".getSingleResult()");
 		}
+		else if ( containerType.equals(Constants.OPTIONAL) ) {
+			unwrapQuery( declaration, unwrap );
+			declaration
+					.append("\n\t\t\t")
+					.append(".uniqueResultOptional()");
+		}
 		else if ( containerType.equals(Constants.LIST) ) {
 			if ( unwrap || hasOrderParameter || hasEnabledFetchProfiles ) {
 				declaration.append("\n\t\t\t");

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/annotation/QueryMethod.java

@@ -152,6 +152,11 @@ else if ( containerTypeName == null ) {
 			declaration
 					.append("\n\t\t\t.getSingleResult()");
 		}
+		else if ( containerTypeName.equals(Constants.OPTIONAL) ) {
+			unwrapQuery( declaration, unwrapped );
+			declaration
+					.append("\n\t\t\t.uniqueResultOptional()");
+		}
 		else if ( containerTypeName.equals(Constants.LIST) ) {
 			declaration
 					.append("\n\t\t\t.getResultList()");

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/util/Constants.java

@@ -100,6 +100,7 @@ public final class Constants {
 	public static final String LIST = java.util.List.class.getName();
 	public static final String MAP = java.util.Map.class.getName();
 	public static final String SET = java.util.Set.class.getName();
+	public static final String OPTIONAL = java.util.Optional.class.getName();
 
 	public static final Map<String, String> COLLECTIONS = Map.of(
 			COLLECTION, Constants.COLLECTION_ATTRIBUTE,