Merge "Add superclasses for gson-jackson migration"

5 files changed, 1563 insertions, 0 deletions

diff --git a/gson/src/test/java/org/onap/policy/common/gson/GsonMessageBodyHandlerTest.java b/gson/src/test/java/org/onap/policy/common/gson/GsonMessageBodyHandlerTest.java
new file mode 100644
index 00000000..85ecfea4
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/GsonMessageBodyHandlerTest.java
@@ -0,0 +1,156 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import javax.ws.rs.core.MediaType;
+import org.junit.Before;
+import org.junit.Test;
+import org.onap.policy.common.gson.GsonMessageBodyHandler;
+
+public class GsonMessageBodyHandlerTest {
+    private static final String GEN_TYPE = "some-type";
+    private static final String[] subtypes = {"json", "jSoN", "hello+json", "javascript", "x-javascript", "x-json"};
+
+    @SuppressWarnings("rawtypes")
+    private static final Class GEN_CLASS = MyObject.class;
+
+    @SuppressWarnings("unchecked")
+    private static final Class<Object> CLASS_OBJ = GEN_CLASS;
+
+    private GsonMessageBodyHandler hdlr;
+
+    @Before
+    public void setUp() {
+        hdlr = new GsonMessageBodyHandler();
+    }
+
+    @Test
+    public void testIsWriteable() {
+        // null media type
+        assertTrue(hdlr.isWriteable(null, null, null, null));
+
+        for (String subtype : subtypes) {
+            assertTrue("writeable " + subtype, hdlr.isWriteable(null, null, null, new MediaType(GEN_TYPE, subtype)));
+
+        }
+
+        // the remaining should be FALSE
+
+        // null subtype
+        assertFalse(hdlr.isWriteable(null, null, null, new MediaType(GEN_TYPE, null)));
+
+        // text subtype
+        assertFalse(hdlr.isWriteable(null, null, null, MediaType.TEXT_HTML_TYPE));
+    }
+
+    @Test
+    public void testGetSize() {
+        assertEquals(-1, hdlr.getSize(null, null, null, null, null));
+    }
+
+    @Test
+    public void testWriteTo_testReadFrom() throws Exception {
+        ByteArrayOutputStream outstr = new ByteArrayOutputStream();
+        MyObject obj1 = new MyObject(10);
+        hdlr.writeTo(obj1, obj1.getClass(), CLASS_OBJ, null, null, null, outstr);
+
+        Object obj2 = hdlr.readFrom(CLASS_OBJ, CLASS_OBJ, null, null, null,
+                        new ByteArrayInputStream(outstr.toByteArray()));
+        assertEquals(obj1.toString(), obj2.toString());
+    }
+
+    @Test
+    public void testWriteTo_DifferentTypes() throws Exception {
+        ByteArrayOutputStream outstr = new ByteArrayOutputStream();
+
+        // use a derived type, but specify the base type when writing
+        MyObject obj1 = new MyObject(10) {};
+        hdlr.writeTo(obj1, obj1.getClass(), CLASS_OBJ, null, null, null, outstr);
+
+        Object obj2 = hdlr.readFrom(CLASS_OBJ, CLASS_OBJ, null, null, null,
+                        new ByteArrayInputStream(outstr.toByteArray()));
+        assertEquals(obj1.toString(), obj2.toString());
+    }
+
+    @Test
+    public void testIsReadable() {
+        // null media type
+        assertTrue(hdlr.isReadable(null, null, null, null));
+
+        // null subtype
+        assertFalse(hdlr.isReadable(null, null, null, new MediaType(GEN_TYPE, null)));
+
+        for (String subtype : subtypes) {
+            assertTrue("readable " + subtype, hdlr.isReadable(null, null, null, new MediaType(GEN_TYPE, subtype)));
+
+        }
+
+        // the remaining should be FALSE
+
+        // null subtype
+        assertFalse(hdlr.isReadable(null, null, null, new MediaType(GEN_TYPE, null)));
+
+        // text subtype
+        assertFalse(hdlr.isReadable(null, null, null, MediaType.TEXT_HTML_TYPE));
+    }
+
+    @Test
+    public void testReadFrom_DifferentTypes() throws Exception {
+        ByteArrayOutputStream outstr = new ByteArrayOutputStream();
+        MyObject obj1 = new MyObject(10);
+        hdlr.writeTo(obj1, obj1.getClass(), CLASS_OBJ, null, null, null, outstr);
+
+        // use a derived type, but specify the base type when reading
+        @SuppressWarnings("rawtypes")
+        Class clazz = new MyObject() {}.getClass();
+
+        @SuppressWarnings("unchecked")
+        Class<Object> objclazz = clazz;
+
+        Object obj2 = hdlr.readFrom(objclazz, CLASS_OBJ, null, null, null,
+                        new ByteArrayInputStream(outstr.toByteArray()));
+        assertEquals(obj1.toString(), obj2.toString());
+    }
+
+    public static class MyObject {
+        private int id;
+
+        public MyObject() {
+            super();
+        }
+
+        public MyObject(int id) {
+            this.id = id;
+        }
+
+        @Override
+        public String toString() {
+            return "MyObject [id=" + id + "]";
+        }
+    }
+
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/JacksonExclusionStrategyTest.java b/gson/src/test/java/org/onap/policy/common/gson/JacksonExclusionStrategyTest.java
new file mode 100644
index 00000000..4b5473c5
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/JacksonExclusionStrategyTest.java
@@ -0,0 +1,203 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gson.FieldAttributes;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
+import java.lang.reflect.GenericArrayType;
+import java.util.LinkedList;
+import java.util.TreeMap;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.onap.policy.common.gson.JacksonExclusionStrategy;
+
+public class JacksonExclusionStrategyTest {
+
+    private static JacksonExclusionStrategy strategy;
+    private static Gson gson;
+
+    @BeforeClass
+    public static void setUpBeforeClass() {
+        strategy = new JacksonExclusionStrategy();
+        gson = new GsonBuilder().setExclusionStrategies(strategy).create();
+    }
+
+    @Test
+    public void testWithGson() {
+        Derived data = new Derived();
+        data.setId(10);
+        data.setText("some text");
+        data.setValue("some value");
+
+        // no fields should be serialized
+        String result = gson.toJson(data);
+        assertEquals("{}", result);
+
+        // no fields should be deserialized
+        result = "{'id':20, 'text':'my text', 'value':'my value'}".replace('\'', '"');
+        Derived data2 = gson.fromJson(result, Derived.class);
+        assertEquals(new Derived().toString(), data2.toString());
+    }
+
+    @Test
+    public void testShouldSkipField() throws Exception {
+        // should skip every field of Data
+        assertTrue(strategy.shouldSkipField(new FieldAttributes(Data.class.getDeclaredField("id"))));
+        assertTrue(strategy.shouldSkipField(new FieldAttributes(Data.class.getDeclaredField("text"))));
+
+        // should not skip fields in Map
+        assertFalse(strategy.shouldSkipField(new FieldAttributes(MyMap.class.getDeclaredField("mapId"))));
+    }
+
+    @Test
+    public void testShouldSkipClass() {
+        assertFalse(strategy.shouldSkipClass(null));
+        assertFalse(strategy.shouldSkipClass(Object.class));
+    }
+
+    @Test
+    public void testIsManaged() {
+        assertTrue(JacksonExclusionStrategy.isManaged(Data.class));
+        assertTrue(JacksonExclusionStrategy.isManaged(Intfc.class));
+        assertTrue(JacksonExclusionStrategy.isManaged(com.google.gson.TypeAdapter.class));
+
+        // generic classes
+        assertFalse(JacksonExclusionStrategy.isManaged(new Data[0].getClass()));
+        assertFalse(JacksonExclusionStrategy.isManaged(Enum.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(boolean.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(byte.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(short.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(int.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(long.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(float.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(double.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(char.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(Boolean.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(Byte.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(Short.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(Integer.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(Long.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(Float.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(Double.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(Character.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(String.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(MyMap.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(MyList.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(MyJson.class));
+        assertFalse(JacksonExclusionStrategy.isManaged(GenericArrayType.class));
+    }
+
+    /**
+     * Used to verify that no fields are exposed.
+     */
+    public static class Data {
+        private int id;
+        public String text;
+
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        public String getText() {
+            return text;
+        }
+
+        public void setText(String text) {
+            this.text = text;
+        }
+
+        @Override
+        public String toString() {
+            return "Data [id=" + id + ", text=" + text + "]";
+        }
+    }
+
+    public static class Derived extends Data {
+        protected String value;
+
+        public String getValue() {
+            return value;
+        }
+
+        public void setValue(String value) {
+            this.value = value;
+        }
+
+        @Override
+        public String toString() {
+            return "Derived [value=" + value + ", " + super.toString() + "]";
+        }
+    }
+
+    /**
+     * Used to verify that enums are not managed.
+     */
+    public static enum Enum {
+        UP, DOWN,
+    }
+
+    /**
+     * Used to verify that interfaces <i>are</i> managed.
+     */
+    public static interface Intfc {
+        int getId();
+    }
+
+    /**
+     * Used to verify that Maps are not managed.
+     */
+    public static class MyMap extends TreeMap<String, Data> {
+        private static final long serialVersionUID = 1L;
+
+        private int mapId;
+
+        public int getMapId() {
+            return mapId;
+        }
+    }
+
+    /**
+     * Used to verify that Collections are not managed.
+     */
+    public static class MyList extends LinkedList<Data> {
+        private static final long serialVersionUID = 1L;
+    }
+
+    /**
+     * Used to verify that JsonElements are not managed.
+     */
+    public static class MyJson extends JsonElement {
+        @Override
+        public JsonElement deepCopy() {
+            return null;
+        }
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/AdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/AdapterTest.java
new file mode 100644
index 00000000..fcb0d9ad
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/AdapterTest.java
@@ -0,0 +1,387 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonPrimitive;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.List;
+import org.junit.Test;
+import org.onap.policy.common.gson.JacksonExclusionStrategy;
+import org.onap.policy.common.gson.annotation.GsonJsonProperty;
+import org.onap.policy.common.gson.internal.Adapter;
+import org.onap.policy.common.gson.internal.DataAdapterFactory.Data;
+import org.onap.policy.common.gson.internal.DataAdapterFactory.DerivedData;
+
+public class AdapterTest {
+    private static final String GET_VALUE_NAME = "getValue";
+    private static final String VALUE_NAME = "value";
+    private static final String MY_NAME = AdapterTest.class.getName();
+
+    private static DataAdapterFactory dataAdapter = new DataAdapterFactory();
+
+    private static Gson gson = new GsonBuilder().registerTypeAdapterFactory(dataAdapter)
+                    .setExclusionStrategies(new JacksonExclusionStrategy()).create();
+
+    /*
+     * The remaining fields are just used within the tests.
+     */
+
+    private String value;
+
+    // empty alias - should use field name
+    @GsonJsonProperty("")
+    protected String emptyAlias;
+
+    @GsonJsonProperty("name-with-alias")
+    protected String nameWithAlias;
+
+    protected String unaliased;
+
+    protected String $invalidFieldName;
+
+    private List<Data> listField;
+
+    private Data dataField;
+
+
+    @Test
+    public void testIsManagedField() {
+        assertTrue(Adapter.isManaged(field(VALUE_NAME)));
+
+        assertFalse(Adapter.isManaged(field("$invalidFieldName")));
+    }
+
+    @Test
+    public void testIsManagedMethod() {
+        assertTrue(Adapter.isManaged(mget(GET_VALUE_NAME)));
+
+        assertFalse(Adapter.isManaged(mget("get$InvalidName")));
+        assertFalse(Adapter.isManaged(mset("set$InvalidName")));
+    }
+
+    @Test
+    public void testAdapterField_Converter() {
+        Adapter adapter = new Adapter(gson, field("dataField"));
+
+        // first, write something of type Data
+        dataAdapter.reset();
+        dataField = new Data(300);
+        JsonElement tree = adapter.toJsonTree(dataField);
+        assertEquals("{'id':300}".replace('\'', '"'), tree.toString());
+
+        // now try a subclass
+        dataAdapter.reset();
+        dataField = new DerivedData(300, "three");
+        tree = adapter.toJsonTree(dataField);
+        assertEquals("{'id':300,'text':'three'}".replace('\'', '"'), tree.toString());
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void testAdapterField_Converter_List() {
+        listField = DataAdapterFactory.makeList();
+
+        Adapter adapter = new Adapter(gson, field("listField"));
+
+        dataAdapter.reset();
+        JsonElement tree = adapter.toJsonTree(listField);
+        assertTrue(dataAdapter.isDataWritten());
+        assertEquals(DataAdapterFactory.ENCODED_LIST, tree.toString());
+
+        // encode it twice so it uses the cached converter
+        dataAdapter.reset();
+        tree = adapter.toJsonTree(listField);
+        assertTrue(dataAdapter.isDataWritten());
+        assertEquals(DataAdapterFactory.ENCODED_LIST, tree.toString());
+
+        dataAdapter.reset();
+        List<Data> lst2 = (List<Data>) adapter.fromJsonTree(tree);
+        assertTrue(dataAdapter.isDataRead());
+
+        assertEquals(listField.toString(), lst2.toString());
+
+        // decode it twice so it uses the cached converter
+        dataAdapter.reset();
+        lst2 = (List<Data>) adapter.fromJsonTree(tree);
+        assertTrue(dataAdapter.isDataRead());
+
+        assertEquals(listField.toString(), lst2.toString());
+    }
+
+    @Test
+    public void testAdapterMethod_Converter() throws Exception {
+        listField = DataAdapterFactory.makeList();
+
+        Method getter = mget("getMyList");
+
+        Adapter aget = new Adapter(gson, getter, true, getter.getReturnType());
+
+        dataAdapter.reset();
+        JsonElement tree = aget.toJsonTree(listField);
+        assertTrue(dataAdapter.isDataWritten());
+        assertEquals(DataAdapterFactory.ENCODED_LIST, tree.toString());
+
+        Method setter = AdapterTest.class.getDeclaredMethod("setMyList", List.class);
+        Adapter aset = new Adapter(gson, setter, true, setter.getGenericParameterTypes()[0]);
+
+        dataAdapter.reset();
+        @SuppressWarnings("unchecked")
+        List<Data> lst2 = (List<Data>) aset.fromJsonTree(tree);
+        assertTrue(dataAdapter.isDataRead());
+
+        assertEquals(listField.toString(), lst2.toString());
+    }
+
+    @Test
+    public void testGetPropName_testGetFullName_testMakeError() {
+        // test field
+        Adapter adapter = new Adapter(gson, field(VALUE_NAME));
+
+        assertEquals(VALUE_NAME, adapter.getPropName());
+        assertEquals(MY_NAME + ".value", adapter.getFullName());
+
+
+        // test getter
+        adapter = new Adapter(gson, mget(GET_VALUE_NAME), true, String.class);
+
+        assertEquals(VALUE_NAME, adapter.getPropName());
+        assertEquals(MY_NAME + ".getValue", adapter.getFullName());
+
+        assertEquals("hello: " + MY_NAME + ".getValue", adapter.makeError("hello: "));
+
+
+        // test setter
+        adapter = new Adapter(gson, mset("setValue"), false, String.class);
+
+        assertEquals(VALUE_NAME, adapter.getPropName());
+        assertEquals(MY_NAME + ".setValue", adapter.getFullName());
+    }
+
+    @Test
+    public void testToJsonTree() {
+        Adapter adapter = new Adapter(gson, field(VALUE_NAME));
+
+        JsonElement tree = adapter.toJsonTree("hello");
+        assertTrue(tree.isJsonPrimitive());
+        assertEquals("hello", tree.getAsString());
+    }
+
+    @Test
+    public void testFromJsonTree() {
+        Adapter adapter = new Adapter(gson, field(VALUE_NAME));
+
+        assertEquals("world", adapter.fromJsonTree(new JsonPrimitive("world")));
+    }
+
+    @Test
+    public void testDetmPropName() {
+        assertEquals("emptyAlias", Adapter.detmPropName(field("emptyAlias")));
+        assertEquals("name-with-alias", Adapter.detmPropName(field("nameWithAlias")));
+        assertEquals("unaliased", Adapter.detmPropName(field("unaliased")));
+        assertEquals(null, Adapter.detmPropName(field("$invalidFieldName")));
+    }
+
+    @Test
+    public void testDetmGetterPropName() {
+        assertEquals("emptyAlias", Adapter.detmGetterPropName(mget("getEmptyAlias")));
+        assertEquals("get-with-alias", Adapter.detmGetterPropName(mget("getWithAlias")));
+        assertEquals("plain", Adapter.detmGetterPropName(mget("getPlain")));
+        assertEquals("primBool", Adapter.detmGetterPropName(mget("isPrimBool")));
+        assertEquals("boxedBool", Adapter.detmGetterPropName(mget("isBoxedBool")));
+        assertEquals(null, Adapter.detmGetterPropName(mget("isString")));
+        assertEquals(null, Adapter.detmGetterPropName(mget("noGet")));
+        assertEquals(null, Adapter.detmGetterPropName(mget("get")));
+        assertEquals(null, Adapter.detmGetterPropName(mget("get$InvalidName")));
+    }
+
+    @Test
+    public void testDetmSetterPropName() {
+        assertEquals("emptyAlias", Adapter.detmSetterPropName(mset("setEmptyAlias")));
+        assertEquals("set-with-alias", Adapter.detmSetterPropName(mset("setWithAlias")));
+        assertEquals("plain", Adapter.detmSetterPropName(mset("setPlain")));
+        assertEquals(null, Adapter.detmSetterPropName(mset("noSet")));
+        assertEquals(null, Adapter.detmSetterPropName(mset("set")));
+        assertEquals(null, Adapter.detmSetterPropName(mset("set$InvalidName")));
+    }
+
+    @Test
+    public void testGetQualifiedNameField() throws Exception {
+        assertEquals(MY_NAME + ".value", Adapter.getQualifiedName(AdapterTest.class.getDeclaredField(VALUE_NAME)));
+    }
+
+    @Test
+    public void testGetQualifiedNameMethod() throws Exception {
+        assertEquals(MY_NAME + ".getValue", Adapter.getQualifiedName(mget(GET_VALUE_NAME)));
+    }
+
+    /**
+     * Gets a field from this class, by name.
+     *
+     * @param name name of the field to get
+     * @return the field
+     */
+    private Field field(String name) {
+        try {
+            return AdapterTest.class.getDeclaredField(name);
+
+        } catch (SecurityException | NoSuchFieldException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Gets a "getter" method from this class, by name.
+     *
+     * @param name name of the method to get
+     * @return the method
+     */
+    private Method mget(String name) {
+        try {
+            return AdapterTest.class.getDeclaredMethod(name);
+
+        } catch (NoSuchMethodException | SecurityException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Gets a "setter" method from this class, by name.
+     *
+     * @param name name of the method to get
+     * @return the method
+     */
+    private Method mset(String name) {
+        try {
+            return AdapterTest.class.getDeclaredMethod(name, String.class);
+
+        } catch (NoSuchMethodException | SecurityException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /*
+     * The remaining methods are just used within the tests.
+     */
+
+    protected String getValue() {
+        return value;
+    }
+
+    // empty alias - should use method name
+    @GsonJsonProperty("")
+    protected String getEmptyAlias() {
+        return "";
+    }
+
+    @GsonJsonProperty("get-with-alias")
+    protected String getWithAlias() {
+        return "";
+    }
+
+    // no alias, begins with "get"
+    protected String getPlain() {
+        return "";
+    }
+
+    // begins with "is", returns primitive boolean
+    protected boolean isPrimBool() {
+        return true;
+    }
+
+    // begins with "is", returns boxed Boolean
+    protected Boolean isBoxedBool() {
+        return true;
+    }
+
+    // begins with "is", but doesn't return a boolean
+    protected String isString() {
+        return "";
+    }
+
+    // doesn't begin with "get"
+    protected String noGet() {
+        return "";
+    }
+
+    // nothing after "get"
+    protected String get() {
+        return "";
+    }
+
+    // name has a bogus character
+    protected String get$InvalidName() {
+        return "";
+    }
+
+
+    protected void setValue(String text) {
+        // do nothing
+    }
+
+    // empty alias - should use method name
+    @GsonJsonProperty("")
+    protected void setEmptyAlias(String text) {
+        // do nothing
+    }
+
+    @GsonJsonProperty("set-with-alias")
+    protected void setWithAlias(String text) {
+        // do nothing
+    }
+
+    // no alias, begins with "set"
+    protected void setPlain(String text) {
+        // do nothing
+    }
+
+    // doesn't begin with "set"
+    protected void noSet(String text) {
+        // do nothing
+    }
+
+    // nothing after "get"
+    protected void set(String text) {
+        // do nothing
+    }
+
+    // name has a bogus character
+    protected void set$InvalidName(String text) {
+        // do nothing
+    }
+
+    // returns a list
+    protected List<Data> getMyList() {
+        return listField;
+    }
+
+    // accepts a list
+    protected void setMyList(List<Data> newList) {
+        listField = newList;
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/ClassWalkerTest.java b/gson/src/test/java/org/onap/policy/common/gson/internal/ClassWalkerTest.java
new file mode 100644
index 00000000..1a15be09
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/ClassWalkerTest.java
@@ -0,0 +1,507 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import com.google.gson.JsonParseException;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.TreeSet;
+import java.util.stream.Collectors;
+import org.junit.Before;
+import org.junit.Test;
+import org.onap.policy.common.gson.annotation.GsonJsonAnyGetter;
+import org.onap.policy.common.gson.annotation.GsonJsonAnySetter;
+import org.onap.policy.common.gson.annotation.GsonJsonIgnore;
+import org.onap.policy.common.gson.annotation.GsonJsonProperty;
+import org.onap.policy.common.gson.internal.Adapter;
+import org.onap.policy.common.gson.internal.ClassWalker;
+
+public class ClassWalkerTest {
+
+    private MyWalker walker;
+
+    /**
+     * Set up.
+     */
+    @Before
+    public void setUp() {
+        walker = new MyWalker();
+    }
+
+    @Test
+    public void testExamineClassOfQ_testExamineField_testExamineInField_testExamineOutField() {
+        walker.walkClassHierarchy(DerivedFromBottom.class);
+
+        assertEquals("[Intfc1, Intfc2, Intfc1, Intfc3, Bottom, DerivedFromBottom]", walker.classes.toString());
+
+        List<String> inFields = walker.getInProps(Field.class).stream().map(field -> field.getName())
+                        .collect(Collectors.toList());
+        Collections.sort(inFields);
+        assertEquals("[exposedField, overriddenValue, transField]", inFields.toString());
+
+        List<String> outFields = walker.getInProps(Field.class).stream().map(field -> field.getName())
+                        .collect(Collectors.toList());
+        Collections.sort(outFields);
+        assertEquals("[exposedField, overriddenValue, transField]", outFields.toString());
+
+        // should work with interfaces without throwing an NPE
+        walker.walkClassHierarchy(Intfc1.class);
+    }
+
+    @Test
+    public void testHasAnyGetter() {
+        walker.walkClassHierarchy(Object.class);
+        assertNull(walker.getAnyGetter());
+        assertNull(walker.getAnySetter());
+
+        walker.walkClassHierarchy(AnyGetterIgnored.class);
+        assertNull(walker.getAnyGetter());
+        assertNull(walker.getAnySetter());
+
+        walker.walkClassHierarchy(AnyGetterOnly.class);
+        assertNotNull(walker.getAnyGetter());
+        assertNull(walker.getAnySetter());
+    }
+
+    @Test
+    public void testHasAnySetter() {
+        walker.walkClassHierarchy(Object.class);
+        assertNull(walker.getAnySetter());
+        assertNull(walker.getAnyGetter());
+
+        walker.walkClassHierarchy(AnySetterIgnored.class);
+        assertNull(walker.getAnySetter());
+        assertNull(walker.getAnyGetter());
+
+        walker.walkClassHierarchy(AnySetterOnly.class);
+        assertNotNull(walker.getAnySetter());
+        assertNull(walker.getAnyGetter());
+    }
+
+    @Test
+    public void testExamineMethod() {
+        walker.walkClassHierarchy(DerivedFromData.class);
+
+        assertEquals("[Data, DerivedFromData]", walker.classes.toString());
+
+        // ensure all methods were examined
+        Collections.sort(walker.methods);
+        List<String> lst = Arrays.asList("getId", "getValue", "getOnlyOut", "getStatic", "getText", "getTheMap",
+                        "getUnserialized", "getValue", "getWithParams", "setExtraParams", "setId", "setMap",
+                        "setMapValue", "setMissingParams", "setNonPublic", "setOnlyIn", "setText", "setUnserialized",
+                        "setValue", "setValue", "wrongGetPrefix", "wrongSetPrefix");
+        Collections.sort(lst);
+        assertEquals(lst.toString(), walker.methods.toString());
+
+        assertNotNull(walker.getAnyGetter());
+        assertEquals("getTheMap", walker.getAnyGetter().getName());
+
+        List<String> getters = walker.getOutProps(Method.class).stream().map(method -> method.getName())
+                        .collect(Collectors.toList());
+        Collections.sort(getters);
+        assertEquals("[getId, getOnlyOut, getValue]", getters.toString());
+
+        assertNotNull(walker.getAnySetter());
+        assertEquals("setMapValue", walker.getAnySetter().getName());
+
+        List<String> setters = walker.getInProps(Method.class).stream().map(method -> method.getName())
+                        .collect(Collectors.toList());
+        Collections.sort(setters);
+        assertEquals("[setId, setOnlyIn, setValue]", setters.toString());
+
+        // getter with invalid parameter count
+        assertThatThrownBy(() -> walker.walkClassHierarchy(AnyGetterMismatchParams.class))
+                        .isInstanceOf(JsonParseException.class).hasMessage(ClassWalker.ANY_GETTER_MISMATCH_ERR
+                                        + AnyGetterMismatchParams.class.getName() + ".getTheMap");
+
+        // setter with too few parameters
+        assertThatThrownBy(() -> walker.walkClassHierarchy(AnySetterTooFewParams.class))
+                        .isInstanceOf(JsonParseException.class).hasMessage(ClassWalker.ANY_SETTER_MISMATCH_ERR
+                                        + AnySetterTooFewParams.class.getName() + ".setOverride");
+
+        // setter with too many parameters
+        assertThatThrownBy(() -> walker.walkClassHierarchy(AnySetterTooManyParams.class))
+                        .isInstanceOf(JsonParseException.class).hasMessage(ClassWalker.ANY_SETTER_MISMATCH_ERR
+                                        + AnySetterTooManyParams.class.getName() + ".setOverride");
+
+        // setter with invalid parameter type
+        assertThatThrownBy(() -> walker.walkClassHierarchy(AnySetterInvalidParam.class))
+                        .isInstanceOf(JsonParseException.class).hasMessage(ClassWalker.ANY_SETTER_TYPE_ERR
+                                        + AnySetterInvalidParam.class.getName() + ".setOverride");
+    }
+
+    @Test
+    public void testExamineMethod_AnyGetter() {
+        walker.walkClassHierarchy(AnyGetterOverride.class);
+
+        assertNotNull(walker.getAnyGetter());
+        assertEquals("getOverride", walker.getAnyGetter().getName());
+    }
+
+    @Test
+    public void testExamineMethod_AnySetter() {
+        walker.walkClassHierarchy(AnySetterOverride.class);
+
+        assertNotNull(walker.getAnySetter());
+        assertEquals("setOverride", walker.getAnySetter().getName());
+    }
+
+    @Test
+    public void testGetInNotIgnored_testGetOutNotIgnored() {
+        walker.walkClassHierarchy(DerivedFromData.class);
+
+        assertEquals("[id, onlyIn, text, value]", new TreeSet<>(walker.getInNotIgnored()).toString());
+        assertEquals("[id, onlyOut, text, value]", new TreeSet<>(walker.getOutNotIgnored()).toString());
+    }
+
+    /**
+     * Walker subclass that records items that are examined.
+     */
+    private static class MyWalker extends ClassWalker {
+        private List<String> classes = new ArrayList<>();
+        private List<String> methods = new ArrayList<>();
+
+        @Override
+        protected void examine(Class<?> clazz) {
+            classes.add(clazz.getSimpleName());
+
+            super.examine(clazz);
+        }
+
+        @Override
+        protected void examine(Method method) {
+            if (Adapter.isManaged(method)) {
+                methods.add(method.getName());
+            }
+
+            super.examine(method);
+        }
+    }
+
+    protected static interface Intfc1 {
+        int id = 1000;
+    }
+
+    protected static interface Intfc2 {
+        String text = "intfc2-text";
+    }
+
+    private static interface Intfc3 {
+
+    }
+
+    protected static class Bottom implements Intfc1, Intfc3 {
+        private int id;
+        public String value;
+
+        public String invalid$fieldName;
+
+        @GsonJsonProperty("exposed")
+        private String exposedField;
+
+        @GsonJsonIgnore
+        public int ignored;
+
+        public transient int ignoredTransField;
+
+        @GsonJsonProperty("trans")
+        public transient int transField;
+
+        @GsonJsonIgnore
+        public int getId() {
+            return id;
+        }
+
+        @GsonJsonIgnore
+        public void setId(int id) {
+            this.id = id;
+        }
+    }
+
+    protected static class DerivedFromBottom extends Bottom implements Intfc1, Intfc2 {
+        private String text;
+        protected String anotherValue;
+
+        @GsonJsonProperty("value")
+        public String overriddenValue;
+
+        @GsonJsonIgnore
+        public String getText() {
+            return text;
+        }
+
+        @GsonJsonIgnore
+        public void setText(String text) {
+            this.text = text;
+        }
+    }
+
+    protected static class Data {
+        private int id;
+        private String text;
+
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        // not public, but property provided
+        @GsonJsonProperty("text")
+        protected String getText() {
+            return text;
+        }
+
+        // this will be ignored, because there's already a field by this name
+        public void setText(String text) {
+            this.text = text;
+        }
+
+        // should only show up in the output list
+        public int getOnlyOut() {
+            return 1100;
+        }
+
+        // will be overridden by subclass
+        @GsonJsonProperty("super-value-getter")
+        public String getValue() {
+            return null;
+        }
+
+        // will be overridden by subclass
+        @GsonJsonProperty("super-value-setter")
+        public void setValue(String value) {
+            // do nothing
+        }
+    }
+
+    protected static class DerivedFromData extends Data {
+        // not serialized
+        private String unserialized;
+
+        // overrides private field and public method from Data
+        public String text;
+
+        private Map<String, String> map;
+
+        private String value;
+
+        public String getValue() {
+            return value;
+        }
+
+        public void setValue(String value) {
+            this.value = value;
+        }
+
+        @GsonJsonAnyGetter
+        public Map<String, String> getTheMap() {
+            return map;
+        }
+
+        @GsonJsonIgnore
+        public void setMap(Map<String, String> map) {
+            this.map = map;
+        }
+
+        @GsonJsonAnySetter
+        public void setMapValue(String key, String value) {
+            if (map == null) {
+                map = new TreeMap<>();
+            }
+
+            map.put(key, value);
+        }
+
+        @GsonJsonIgnore
+        public String getUnserialized() {
+            return unserialized;
+        }
+
+        @GsonJsonIgnore
+        public void setUnserialized(String unserialized) {
+            this.unserialized = unserialized;
+        }
+
+        // should only show up in the input list
+        public void setOnlyIn(int value) {
+            // do nothing
+        }
+
+        // has a param - shouldn't be serialized
+        public int getWithParams(String text) {
+            return 1000;
+        }
+
+        // too few params - shouldn't be serialized
+        public void setMissingParams() {
+            // do nothing
+        }
+
+        // too many params - shouldn't be serialized
+        public void setExtraParams(String text, String moreText) {
+            // do nothing
+        }
+
+        // not public - shouldn't be serialized
+        protected void setNonPublic(String text) {
+            // do nothing
+        }
+
+        // doesn't start with "get"
+        public String wrongGetPrefix() {
+            return null;
+        }
+
+        // doesn't start with "set"
+        public void wrongSetPrefix(String text) {
+            // do nothing
+        }
+
+        // static
+        public static String getStatic() {
+            return null;
+        }
+    }
+
+    /**
+     * The "get" method has an incorrect argument count.
+     */
+    private static class AnyGetterMismatchParams {
+        @GsonJsonAnyGetter
+        public Map<String, String> getTheMap(String arg) {
+            return new TreeMap<>();
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnyGetter} method.
+     */
+    private static class AnyGetterOnly {
+        @GsonJsonAnyGetter
+        private Map<String, Integer> getOverride() {
+            return null;
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnyGetter} method, but it's ignored.
+     */
+    private static class AnyGetterIgnored {
+        @GsonJsonAnyGetter
+        @GsonJsonIgnore
+        private Map<String, Integer> getOverride() {
+            return null;
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnySetter} method.
+     */
+    private static class AnySetterOnly {
+        @GsonJsonAnySetter
+        private void setOverride(String key, int value) {
+            // do nothing
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnySetter} method, but it's ignored.
+     */
+    private static class AnySetterIgnored {
+        @GsonJsonAnySetter
+        @GsonJsonIgnore
+        private void setOverride(String key, int value) {
+            // do nothing
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnyGetter} method that overrides the super class' method.
+     */
+    private static class AnyGetterOverride extends DerivedFromData {
+        private Map<String, Integer> overMap;
+
+        @GsonJsonAnyGetter
+        private Map<String, Integer> getOverride() {
+            return overMap;
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnySetter} method that overrides the super class' method.
+     */
+    private static class AnySetterOverride extends DerivedFromData {
+        private Map<String, Integer> overMap;
+
+        @GsonJsonAnySetter
+        private void setOverride(String key, int value) {
+            if (overMap == null) {
+                overMap = new TreeMap<>();
+            }
+
+            overMap.put(key, value);
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnySetter} method with too few parameters.
+     */
+    private static class AnySetterTooFewParams extends DerivedFromData {
+        @GsonJsonAnySetter
+        public void setOverride(String key) {
+            // do nothing
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnySetter} method with too few parameters.
+     */
+    private static class AnySetterTooManyParams extends DerivedFromData {
+        @GsonJsonAnySetter
+        public void setOverride(String key, int value, String anotherValue) {
+            // do nothing
+        }
+    }
+
+    /**
+     * Has {@link GsonJsonAnySetter} method whose first argument type is incorrect.
+     */
+    private static class AnySetterInvalidParam extends DerivedFromData {
+        @GsonJsonAnySetter
+        public void setOverride(Integer key, String value) {
+            // do nothing
+        }
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/internal/DataAdapterFactory.java b/gson/src/test/java/org/onap/policy/common/gson/internal/DataAdapterFactory.java
new file mode 100644
index 00000000..d0f0b1ec
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/internal/DataAdapterFactory.java
@@ -0,0 +1,310 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * Factory used with test Data.
+ */
+public class DataAdapterFactory implements TypeAdapterFactory {
+
+    /**
+     * Output of {@link #makeList()}, encoded as json.
+     */
+    public static final String ENCODED_LIST = "[{'id':100},{'id':101}]".replace('\'', '"');
+
+    /**
+     * Output of {@link #makeMap()}, encoded as json.
+     */
+    public static final String ENCODED_MAP = "'data-100':{'id':100},'data-101':{'id':101}".replace('\'', '"');
+
+    /**
+     * Object handled by this factory.
+     */
+    public static class Data {
+        private int id;
+
+        public Data() {
+            super();
+        }
+
+        public Data(int id) {
+            this.id = id;
+        }
+
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        @Override
+        public String toString() {
+            return "Data [id=" + id + "]";
+        }
+    }
+
+    /**
+     * Object derived from Data.
+     */
+    public static class DerivedData extends Data {
+        private String text;
+
+        public DerivedData() {
+            super();
+        }
+
+        public DerivedData(int id, String text) {
+            super(id);
+            this.text = text;
+        }
+
+        public String getText() {
+            return text;
+        }
+
+        public void setText(String text) {
+            this.text = text;
+        }
+
+        @Override
+        public String toString() {
+            return "DerivedData [text=" + text + ", toString()=" + super.toString() + "]";
+        }
+    }
+
+    /**
+     * Set to {@code true} when {@link #write(JsonWriter, Data)} has been invoked.
+     */
+    private boolean dataWritten = false;
+
+    /**
+     * Set to {@code true} when {@link #read(JsonReader)} has been invoked.
+     */
+    private boolean dataRead = false;
+
+    /**
+     * Clears the flags that indicate that "read" or "write" has been invoked.
+     */
+    public void reset() {
+        dataWritten = true;
+        dataRead = true;
+    }
+
+    public boolean isDataWritten() {
+        return dataWritten;
+    }
+
+    public boolean isDataRead() {
+        return dataRead;
+    }
+
+    /**
+     * Makes a list of Data.
+     *
+     * @return a new list of Data
+     */
+    public static List<Data> makeList() {
+        List<Data> listField = new ArrayList<>();
+
+        listField.add(new Data(100));
+        listField.add(new Data(101));
+
+        return listField;
+    }
+
+    /**
+     * Makes an array of Data.
+     *
+     * @return a new array of Data
+     */
+    public static JsonArray makeArray() {
+        JsonArray arr = new JsonArray();
+
+        for (Data data : makeList()) {
+            JsonObject json = new JsonObject();
+            json.addProperty("id", data.getId());
+            arr.add(json);
+        }
+
+        return arr;
+    }
+
+    /**
+     * Makes a map of Data.
+     *
+     * @return a new map of Data
+     */
+    public static Map<String, List<Data>> makeMap() {
+        Map<String, List<Data>> map = new TreeMap<>();
+
+        for (Data data : makeList()) {
+            map.put("data-" + data.getId(), Arrays.asList(data));
+        }
+
+        return map;
+    }
+
+    /**
+     * Adds Data objects to a tree, mirroring {@link #makeMap()}.
+     *
+     * @param tree tree into which objects are to be added
+     */
+    public static void addToObject(JsonObject tree) {
+        for (JsonElement ent : makeArray()) {
+            JsonObject obj = ent.getAsJsonObject();
+            JsonArray arr = new JsonArray();
+            arr.add(obj);
+            tree.add("data-" + obj.get("id").getAsString(), arr);
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+        if (type.getRawType() == Data.class) {
+            return (TypeAdapter<T>) new DataTypeAdapter(gson.getDelegateAdapter(this, TypeToken.get(Data.class)),
+                            gson.getAdapter(JsonElement.class));
+        }
+
+        if (type.getRawType() == DerivedData.class) {
+            return (TypeAdapter<T>) new DerivedDataTypeAdapter(
+                            gson.getDelegateAdapter(this, TypeToken.get(DerivedData.class)),
+                            gson.getAdapter(JsonElement.class));
+        }
+
+        return null;
+    }
+
+    /**
+     * Adapter for "Data".
+     */
+    private class DataTypeAdapter extends TypeAdapter<Data> {
+        private TypeAdapter<Data> delegate;
+        private TypeAdapter<JsonElement> elementAdapter;
+
+        /**
+         * Constructs the object.
+         *
+         * @param delegate delegate adapter
+         * @param elementAdapter element adapter
+         */
+        public DataTypeAdapter(TypeAdapter<Data> delegate, TypeAdapter<JsonElement> elementAdapter) {
+            this.delegate = delegate;
+            this.elementAdapter = elementAdapter;
+        }
+
+        @Override
+        public void write(JsonWriter out, Data data) throws IOException {
+            dataWritten = true;
+
+            JsonElement tree = delegate.toJsonTree(data);
+
+            if (tree.isJsonObject()) {
+                JsonObject jsonObj = tree.getAsJsonObject();
+                jsonObj.addProperty("id", data.getId());
+            }
+
+            elementAdapter.write(out, tree);
+        }
+
+        @Override
+        public Data read(JsonReader in) throws IOException {
+            dataRead = true;
+
+            JsonElement tree = elementAdapter.read(in);
+            Data data = delegate.fromJsonTree(tree);
+
+            if (tree.isJsonObject()) {
+                JsonObject jsonObj = tree.getAsJsonObject();
+                data.setId(jsonObj.get("id").getAsInt());
+            }
+
+            return data;
+        }
+    }
+    /**
+     * Adapter for "DerivedData".
+     */
+    private class DerivedDataTypeAdapter extends TypeAdapter<DerivedData> {
+        private TypeAdapter<DerivedData> delegate;
+        private TypeAdapter<JsonElement> elementAdapter;
+
+        /**
+         * Constructs the object.
+         *
+         * @param delegate delegate adapter
+         * @param elementAdapter element adapter
+         */
+        public DerivedDataTypeAdapter(TypeAdapter<DerivedData> delegate, TypeAdapter<JsonElement> elementAdapter) {
+            this.delegate = delegate;
+            this.elementAdapter = elementAdapter;
+        }
+
+        @Override
+        public void write(JsonWriter out, DerivedData data) throws IOException {
+            dataWritten = true;
+
+            JsonElement tree = delegate.toJsonTree(data);
+
+            if (tree.isJsonObject()) {
+                JsonObject jsonObj = tree.getAsJsonObject();
+                jsonObj.addProperty("id", data.getId());
+                jsonObj.addProperty("text", data.getText());
+            }
+
+            elementAdapter.write(out, tree);
+        }
+
+        @Override
+        public DerivedData read(JsonReader in) throws IOException {
+            dataRead = true;
+
+            JsonElement tree = elementAdapter.read(in);
+            DerivedData data = delegate.fromJsonTree(tree);
+
+            if (tree.isJsonObject()) {
+                JsonObject jsonObj = tree.getAsJsonObject();
+                data.setId(jsonObj.get("id").getAsInt());
+                data.setText(jsonObj.get("text").getAsString());
+            }
+
+            return data;
+        }
+    }
+}