Deserializing only matching input to JsonValue subinterfaces

src/main/java/org/eclipse/yasson/internal/deserializer/types/JsonObjectDeserializer.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2025 Oracle and/or its affiliates. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0,
+ * or the Eclipse Distribution License v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+ */
+
+package org.eclipse.yasson.internal.deserializer.types;
+
+import jakarta.json.JsonObject;
+import jakarta.json.bind.JsonbException;
+import jakarta.json.stream.JsonParser;
+
+import org.eclipse.yasson.internal.DeserializationContextImpl;
+import org.eclipse.yasson.internal.deserializer.ModelDeserializer;
+import org.eclipse.yasson.internal.properties.MessageKeys;
+import org.eclipse.yasson.internal.properties.Messages;
+
+/**
+ * Deserializer of the {@link JsonObject} type.
+ */
+class JsonObjectDeserializer implements ModelDeserializer<JsonParser> {
+
+    private final ModelDeserializer<Object> delegate;
+
+    JsonObjectDeserializer(TypeDeserializerBuilder builder) {
+        this.delegate = builder.getDelegate();
+    }
+
+    @Override
+    public Object deserialize(JsonParser value, DeserializationContextImpl context) {
+        JsonParser.Event last = context.getLastValueEvent();
+        return delegate.deserialize(deserializeValue(last, value), context);
+    }
+
+    private JsonObject deserializeValue(JsonParser.Event last, JsonParser parser) {
+        switch (last) {
+        case VALUE_NULL:
+            return null;
+        case START_OBJECT:
+            return parser.getObject();
+        default:
+            throw new JsonbException(Messages.getMessage(MessageKeys.INVALID_DESERIALIZATION_JSON_TYPE, last));
+        }
+    }
+}

src/main/java/org/eclipse/yasson/internal/deserializer/types/TypeDeserializers.java

@@ -47,6 +47,7 @@
 
 import javax.xml.datatype.XMLGregorianCalendar;
 
+import jakarta.json.JsonObject;
 import jakarta.json.JsonValue;
 import jakarta.json.bind.JsonbException;
 import jakarta.json.stream.JsonParser;
@@ -173,6 +174,8 @@ public static ModelDeserializer<JsonParser> getTypeDeserializer(Class<?> clazz,
 
         if (JsonValue.class.equals(clazz)) {
             return new JsonValueDeserializer(builder, JsonValue.NULL);
+        } else if (JsonObject.class.equals(clazz)) {
+            return new JsonObjectDeserializer(builder);
         } else if (JsonValue.class.isAssignableFrom(clazz)) {
             return new JsonValueDeserializer(builder, null);
         }

src/test/java/org/eclipse/yasson/defaultmapping/jsonp/JsonpTest.java

@@ -13,6 +13,7 @@
 package org.eclipse.yasson.defaultmapping.jsonp;
 
 import java.math.BigDecimal;
+import java.util.List;
 
 import jakarta.json.Json;
 import jakarta.json.JsonArray;
@@ -29,6 +30,7 @@
 import org.eclipse.yasson.defaultmapping.jsonp.model.JsonpPojo;
 import org.junit.jupiter.api.Test;
 
+import static org.eclipse.yasson.Assertions.shouldFail;
 import static org.eclipse.yasson.Jsonbs.defaultJsonb;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.CoreMatchers.nullValue;
@@ -85,6 +87,16 @@ public void testInnerJsonObject() {
 
     }
 
+    @Test
+    public void testDeserializeNonObject() {
+        final JsonValue jsonString = Json.createValue("test");
+        final JsonValue jsonNumber = Json.createValue(1);
+        for (JsonValue v : List.of(jsonString, jsonNumber, JsonValue.TRUE, JsonValue.EMPTY_JSON_ARRAY)) {
+            // Non-object JSON input should not be serialized into JsonObject
+            shouldFail(() -> defaultJsonb.fromJson(v.toString(), JsonObject.class));
+        }
+    }
+
     @Test
     public void testMarshallJsonArray() {