Add gson adapters for special field types

Added type adapters for Instant, LocalDateTime, and ZonedDateTime.  UUID
seems to work already.
Added new Coder that offers an alternative encoding for Instant.

Issue-ID: POLICY-1625
Signed-off-by: Jim Hahn <jrh3@att.com>
Change-Id: I5230fa7fe955d78c5f2da1316cb1504b5875ea84

10 files changed, 582 insertions, 3 deletions

diff --git a/gson/src/main/java/org/onap/policy/common/gson/GsonMessageBodyHandler.java b/gson/src/main/java/org/onap/policy/common/gson/GsonMessageBodyHandler.java
index 75d58f2f..d6e36b39 100644
--- a/gson/src/main/java/org/onap/policy/common/gson/GsonMessageBodyHandler.java
+++ b/gson/src/main/java/org/onap/policy/common/gson/GsonMessageBodyHandler.java
@@ -2,7 +2,7 @@
  * ============LICENSE_START=======================================================
  * ONAP
  * ================================================================================
- * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2019-2020 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.
@@ -30,6 +30,9 @@ import java.io.OutputStreamWriter;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Type;
 import java.nio.charset.StandardCharsets;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZonedDateTime;
 import javax.ws.rs.Consumes;
 import javax.ws.rs.Produces;
 import javax.ws.rs.core.MediaType;
@@ -85,7 +88,10 @@ public class GsonMessageBodyHandler implements MessageBodyReader<Object>, Messag
      * @return the configured builder
      */
     public static GsonBuilder configBuilder(GsonBuilder builder) {
-        return builder.disableHtmlEscaping().registerTypeAdapterFactory(new MapDoubleAdapterFactory());
+        return builder.disableHtmlEscaping().registerTypeAdapterFactory(new MapDoubleAdapterFactory())
+                        .registerTypeAdapter(Instant.class, new InstantTypeAdapter())
+                        .registerTypeAdapter(LocalDateTime.class, new LocalDateTimeTypeAdapter())
+                        .registerTypeAdapter(ZonedDateTime.class, new ZonedDateTimeTypeAdapter());
     }
 
     @Override
diff --git a/gson/src/main/java/org/onap/policy/common/gson/InstantAsMillisTypeAdapter.java b/gson/src/main/java/org/onap/policy/common/gson/InstantAsMillisTypeAdapter.java
new file mode 100644
index 00000000..6bcfaac3
--- /dev/null
+++ b/gson/src/main/java/org/onap/policy/common/gson/InstantAsMillisTypeAdapter.java
@@ -0,0 +1,58 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 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 com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.time.Instant;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * GSON Type Adapter for "Instant" fields, that encodes them as milliseconds.
+ */
+public class InstantAsMillisTypeAdapter extends TypeAdapter<Instant> {
+
+    @Override
+    public void write(JsonWriter out, Instant value) throws IOException {
+        if (value == null) {
+            out.nullValue();
+        } else {
+            long epochMillis = TimeUnit.MILLISECONDS.convert(value.getEpochSecond(), TimeUnit.SECONDS);
+            long nanoMillis = TimeUnit.MILLISECONDS.convert(value.getNano(), TimeUnit.NANOSECONDS);
+            long millis = epochMillis + nanoMillis;
+            out.value(millis);
+        }
+    }
+
+    @Override
+    public Instant read(JsonReader in) throws IOException {
+        if (in.peek() == JsonToken.NULL) {
+            in.nextNull();
+            return null;
+        } else {
+            long millis = in.nextLong();
+            return Instant.ofEpochMilli(millis);
+        }
+    }
+}
diff --git a/gson/src/main/java/org/onap/policy/common/gson/InstantTypeAdapter.java b/gson/src/main/java/org/onap/policy/common/gson/InstantTypeAdapter.java
new file mode 100644
index 00000000..9ebf2baa
--- /dev/null
+++ b/gson/src/main/java/org/onap/policy/common/gson/InstantTypeAdapter.java
@@ -0,0 +1,60 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 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 com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.time.Instant;
+import java.time.format.DateTimeParseException;
+
+/**
+ * GSON Type Adapter for "Instant" fields, that uses the standard ISO_INSTANT formatter.
+ */
+public class InstantTypeAdapter extends TypeAdapter<Instant> {
+
+    @Override
+    public void write(JsonWriter out, Instant value) throws IOException {
+        if (value == null) {
+            out.nullValue();
+        } else {
+            out.value(value.toString());
+        }
+    }
+
+    @Override
+    public Instant read(JsonReader in) throws IOException {
+        try {
+            if (in.peek() == JsonToken.NULL) {
+                in.nextNull();
+                return null;
+            } else {
+                String text = in.nextString();
+                return Instant.parse(text);
+            }
+
+        } catch (DateTimeParseException e) {
+            throw new IOException("invalid date", e);
+        }
+    }
+}
diff --git a/gson/src/main/java/org/onap/policy/common/gson/LocalDateTimeTypeAdapter.java b/gson/src/main/java/org/onap/policy/common/gson/LocalDateTimeTypeAdapter.java
new file mode 100644
index 00000000..2b297cbf
--- /dev/null
+++ b/gson/src/main/java/org/onap/policy/common/gson/LocalDateTimeTypeAdapter.java
@@ -0,0 +1,64 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 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 com.google.gson.JsonParseException;
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+
+/**
+ * GSON Type Adapter for "LocalDateTime" fields, that uses the standard
+ * ISO_LOCAL_DATE_TIME formatter.
+ */
+public class LocalDateTimeTypeAdapter extends TypeAdapter<LocalDateTime> {
+    private static final DateTimeFormatter FORMATTER = DateTimeFormatter.ISO_LOCAL_DATE_TIME;
+
+    @Override
+    public LocalDateTime read(JsonReader in) throws IOException {
+        try {
+            if (in.peek() == JsonToken.NULL) {
+                in.nextNull();
+                return null;
+            } else {
+                return LocalDateTime.parse(in.nextString(), FORMATTER);
+            }
+
+        } catch (DateTimeParseException e) {
+            throw new JsonParseException("invalid date", e);
+        }
+    }
+
+    @Override
+    public void write(JsonWriter out, LocalDateTime value) throws IOException {
+        if (value == null) {
+            out.nullValue();
+        } else {
+            String text = value.format(FORMATTER);
+            out.value(text);
+        }
+    }
+}
diff --git a/gson/src/main/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapter.java b/gson/src/main/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapter.java
new file mode 100644
index 00000000..147fb03d
--- /dev/null
+++ b/gson/src/main/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapter.java
@@ -0,0 +1,64 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 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 com.google.gson.JsonParseException;
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+
+/**
+ * GSON Type Adapter for "ZonedDateTime" fields, that uses the standard
+ * ISO_ZONED_DATE_TIME formatter.
+ */
+public class ZonedDateTimeTypeAdapter extends TypeAdapter<ZonedDateTime> {
+    private static final DateTimeFormatter FORMATTER = DateTimeFormatter.ISO_ZONED_DATE_TIME;
+
+    @Override
+    public ZonedDateTime read(JsonReader in) throws IOException {
+        try {
+            if (in.peek() == JsonToken.NULL) {
+                in.nextNull();
+                return null;
+            } else {
+                return ZonedDateTime.parse(in.nextString(), FORMATTER);
+            }
+
+        } catch (DateTimeParseException e) {
+            throw new JsonParseException("invalid date", e);
+        }
+    }
+
+    @Override
+    public void write(JsonWriter out, ZonedDateTime value) throws IOException {
+        if (value == null) {
+            out.nullValue();
+        } else {
+            String text = value.format(FORMATTER);
+            out.value(text);
+        }
+    }
+}
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
index f1740ac1..c05a1e51 100644
--- a/gson/src/test/java/org/onap/policy/common/gson/GsonMessageBodyHandlerTest.java
+++ b/gson/src/test/java/org/onap/policy/common/gson/GsonMessageBodyHandlerTest.java
@@ -2,7 +2,7 @@
  * ============LICENSE_START=======================================================
  * ONAP
  * ================================================================================
- * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2019-2020 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.
@@ -20,15 +20,24 @@
 
 package org.onap.policy.common.gson;
 
+import static org.assertj.core.api.Assertions.assertThat;
 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 java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.UUID;
 import javax.ws.rs.core.MediaType;
+import lombok.ToString;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -160,6 +169,32 @@ public class GsonMessageBodyHandlerTest {
         assertEquals(12.5, map.props.get("doubleVal"));
     }
 
+    @Test
+    public void testInterestingFields() throws IOException {
+        InterestingFields data = new InterestingFields();
+        data.instant = Instant.ofEpochMilli(1583249713500L);
+        data.uuid = UUID.fromString("a850cb9f-3c5e-417c-abfd-0679cdcd1ab0");
+        data.localDate = LocalDateTime.of(2020, 2, 3, 4, 5, 6, 789000000);
+        data.zonedDate = ZonedDateTime.of(2020, 2, 3, 4, 5, 6, 789000000, ZoneId.of("US/Eastern"));
+
+        ByteArrayOutputStream outstr = new ByteArrayOutputStream();
+        hdlr.writeTo(data, data.getClass(), data.getClass(), null, null, null, outstr);
+
+        // ensure fields are encoded as expected
+
+        // @formatter:off
+        assertThat(outstr.toString(StandardCharsets.UTF_8))
+                            .contains("\"2020-03-03T15:35:13.500Z\"")
+                            .contains("\"2020-02-03T04:05:06.789\"")
+                            .contains("\"2020-02-03T04:05:06.789-05:00[US/Eastern]\"")
+                            .contains("a850cb9f-3c5e-417c-abfd-0679cdcd1ab0");
+        // @formatter:on
+
+        Object obj2 = hdlr.readFrom(Object.class, data.getClass(), null, null, null,
+                        new ByteArrayInputStream(outstr.toByteArray()));
+        assertEquals(data.toString(), obj2.toString());
+    }
+
 
     public static class MyObject {
         private int id;
@@ -186,4 +221,12 @@ public class GsonMessageBodyHandlerTest {
             return props.toString();
         }
     }
+
+    @ToString
+    private static class InterestingFields {
+        private LocalDateTime localDate;
+        private Instant instant;
+        private UUID uuid;
+        private ZonedDateTime zonedDate;
+    }
 }
diff --git a/gson/src/test/java/org/onap/policy/common/gson/InstantAsMillisTypeAdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/InstantAsMillisTypeAdapterTest.java
new file mode 100644
index 00000000..c48919a7
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/InstantAsMillisTypeAdapterTest.java
@@ -0,0 +1,66 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 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.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertEquals;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import java.time.Instant;
+import lombok.ToString;
+import org.junit.Test;
+
+public class InstantAsMillisTypeAdapterTest {
+    private static Gson gson =
+                    new GsonBuilder().registerTypeAdapter(Instant.class, new InstantAsMillisTypeAdapter()).create();
+
+    @Test
+    public void test() {
+        InterestingFields data = new InterestingFields();
+        data.instant = Instant.ofEpochMilli(1583249713500L);
+
+        String json = gson.toJson(data);
+
+        // instant should be encoded as a number, without quotes
+        assertThat(json).doesNotContain("nanos").contains("1583249713500").doesNotContain("\"1583249713500\"")
+                        .doesNotContain("T");
+
+        InterestingFields data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // null output
+        data.instant = null;
+        json = gson.toJson(data);
+        data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // null input
+        data2 = gson.fromJson("{\"instant\":null}", InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+    }
+
+
+    @ToString
+    private static class InterestingFields {
+        private Instant instant;
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/InstantTypeAdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/InstantTypeAdapterTest.java
new file mode 100644
index 00000000..97219d0d
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/InstantTypeAdapterTest.java
@@ -0,0 +1,73 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 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.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParseException;
+import java.time.Instant;
+import lombok.ToString;
+import org.junit.Test;
+
+public class InstantTypeAdapterTest {
+    private static Gson gson =
+                    new GsonBuilder().registerTypeAdapter(Instant.class, new InstantTypeAdapter()).create();
+
+    @Test
+    public void test() {
+        InterestingFields data = new InterestingFields();
+        data.instant = Instant.ofEpochMilli(1583249713500L);
+
+        String json = gson.toJson(data);
+
+        // instant should be encoded as a number, without quotes
+        assertThat(json).doesNotContain("nanos").contains("\"2020-03-03T15:35:13.500Z\"")
+                        .doesNotContain("1583249713500");
+
+        InterestingFields data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // try when the date-time string is invalid
+        String json2 = json.replace("2020", "invalid-date");
+        assertThatThrownBy(() -> gson.fromJson(json2, InterestingFields.class)).isInstanceOf(JsonParseException.class)
+                        .hasMessageContaining("invalid date");
+
+        // null output
+        data.instant = null;
+        json = gson.toJson(data);
+        data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // null input
+        data2 = gson.fromJson("{\"instant\":null}", InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+    }
+
+
+    @ToString
+    private static class InterestingFields {
+        private Instant instant;
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/LocalDateTimeTypeAdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/LocalDateTimeTypeAdapterTest.java
new file mode 100644
index 00000000..2778a4ba
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/LocalDateTimeTypeAdapterTest.java
@@ -0,0 +1,72 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 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.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParseException;
+import java.time.LocalDateTime;
+import lombok.ToString;
+import org.junit.Test;
+
+public class LocalDateTimeTypeAdapterTest {
+    private static Gson gson =
+                    new GsonBuilder().registerTypeAdapter(LocalDateTime.class, new LocalDateTimeTypeAdapter()).create();
+
+    @Test
+    public void test() {
+        InterestingFields data = new InterestingFields();
+        data.date = LocalDateTime.of(2020, 2, 3, 4, 5, 6, 789000000);
+
+        String json = gson.toJson(data);
+
+        // instant should be encoded as a number, without quotes
+        assertThat(json).doesNotContain("year").contains("\"2020-02-03T04:05:06.789\"");
+
+        InterestingFields data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // try when the date-time string is invalid
+        String json2 = json.replace("2020", "invalid-date");
+        assertThatThrownBy(() -> gson.fromJson(json2, InterestingFields.class)).isInstanceOf(JsonParseException.class)
+                        .hasMessageContaining("invalid date");
+
+        // null output
+        data.date = null;
+        json = gson.toJson(data);
+        data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // null input
+        data2 = gson.fromJson("{\"date\":null}", InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+    }
+
+
+    @ToString
+    private static class InterestingFields {
+        private LocalDateTime date;
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapterTest.java
new file mode 100644
index 00000000..766a979d
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapterTest.java
@@ -0,0 +1,73 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2020 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.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParseException;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import lombok.ToString;
+import org.junit.Test;
+
+public class ZonedDateTimeTypeAdapterTest {
+    private static Gson gson =
+                    new GsonBuilder().registerTypeAdapter(ZonedDateTime.class, new ZonedDateTimeTypeAdapter()).create();
+
+    @Test
+    public void test() {
+        InterestingFields data = new InterestingFields();
+        data.date = ZonedDateTime.of(2020, 2, 3, 4, 5, 6, 789000000, ZoneId.of("US/Eastern"));
+
+        String json = gson.toJson(data);
+
+        // instant should be encoded as a number, without quotes
+        assertThat(json).doesNotContain("year").contains("\"2020-02-03T04:05:06.789-05:00[US/Eastern]\"");
+
+        InterestingFields data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // try when the date-time string is invalid
+        String json2 = json.replace("2020", "invalid-date");
+        assertThatThrownBy(() -> gson.fromJson(json2, InterestingFields.class)).isInstanceOf(JsonParseException.class)
+                        .hasMessageContaining("invalid date");
+
+        // null output
+        data.date = null;
+        json = gson.toJson(data);
+        data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // null input
+        data2 = gson.fromJson("{\"date\":null}", InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+    }
+
+
+    @ToString
+    private static class InterestingFields {
+        private ZonedDateTime date;
+    }
+}