Add DataRouter Subscriber

Change-Id: I7f81c3d7249dcfcf00e2c7f3272f478d2346397d
Issue-ID: DCAEGEN2-1079
Signed-off-by: JoeOLeary <joseph.o.leary@est.tech>

10 files changed, 531 insertions, 0 deletions

diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/App.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/App.java
new file mode 100644
index 0000000..2b93d03
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/App.java
@@ -0,0 +1,50 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.dcaegen2.services.pmmapper;
+
+import io.undertow.Handlers;
+import io.undertow.Undertow;
+import io.undertow.util.StatusCodes;
+import org.onap.dcaegen2.services.pmmapper.config.BusControllerConfig;
+import org.onap.dcaegen2.services.pmmapper.datarouter.DataRouterSubscriber;
+import org.onap.dcaegen2.services.pmmapper.exceptions.TooManyTriesException;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+
+public class App {
+
+    public static void main(String[] args) throws MalformedURLException, InterruptedException, TooManyTriesException {
+        DataRouterSubscriber dataRouterSubscriber = new DataRouterSubscriber(event -> {
+            event.getHttpServerExchange().unDispatch();
+            event.getHttpServerExchange().getResponseSender().send(StatusCodes.OK_STRING);
+            System.out.println(event.getMetadata().getProductName());
+        });
+        BusControllerConfig config = new BusControllerConfig();
+        config.setDataRouterSubscribeEndpoint(new URL("http://" + System.getenv("DMAAP_BC_SERVICE_HOST") + ":" + System.getenv("DMAAP_BC_SERVICE_PORT") + "/webapi/dr_subs"));
+        dataRouterSubscriber.start(config);
+
+        Undertow.builder()
+                .addHttpListener(8081, "0.0.0.0")
+                .setHandler(Handlers.routing().add("put", "/sub", dataRouterSubscriber))
+                .build().start();
+    }
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/config/BusControllerConfig.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/config/BusControllerConfig.java
new file mode 100644
index 0000000..63b2a32
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/config/BusControllerConfig.java
@@ -0,0 +1,40 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcaegen2.services.pmmapper.config;
+
+import lombok.Data;
+
+import java.net.URL;
+
+/**
+ * Stub for BusControllerConfiguration object.
+ */
+@Data
+public class BusControllerConfig {
+
+    private String dcaeLocation = "dcaeLocation";
+    private String deliveryURL = "deliveryURL";
+    private int feedId = 2;
+    private String lastMod = "lastMod";
+    private String username = "username";
+    private String password = "password";
+    private URL dataRouterSubscribeEndpoint;
+
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/datarouter/DataRouterSubscriber.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/datarouter/DataRouterSubscriber.java
new file mode 100644
index 0000000..1d27d3b
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/datarouter/DataRouterSubscriber.java
@@ -0,0 +1,177 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.dcaegen2.services.pmmapper.datarouter;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import io.undertow.util.HeaderValues;
+import lombok.Data;
+import lombok.NonNull;
+import org.onap.dcaegen2.services.pmmapper.config.BusControllerConfig;
+import org.onap.dcaegen2.services.pmmapper.exceptions.NoMetadataException;
+import org.onap.dcaegen2.services.pmmapper.exceptions.TooManyTriesException;
+import org.onap.dcaegen2.services.pmmapper.model.EventMetadata;
+import org.onap.dcaegen2.services.pmmapper.model.Event;
+import io.undertow.server.HttpHandler;
+import io.undertow.server.HttpServerExchange;
+import io.undertow.util.StatusCodes;
+
+import lombok.extern.slf4j.Slf4j;
+import org.onap.dcaegen2.services.pmmapper.utils.RequiredFieldDeserializer;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.net.HttpURLConnection;
+import java.nio.charset.StandardCharsets;
+import java.util.Optional;
+import java.util.Random;
+
+/**
+ * Subscriber for events sent from data router
+ * Provides an undertow HttpHandler to be used as an endpoint for data router to send events to.
+ */
+@Slf4j
+@Data
+public class DataRouterSubscriber implements HttpHandler {
+
+    private static final int NUMBER_OF_ATTEMPTS = 5;
+    private static final int DEFAULT_TIMEOUT = 2000;
+    private static final int MAX_JITTER = 50;
+
+    private static final String METADATA_HEADER = "X-ATT-DR-META";
+    private static final String BAD_METADATA_MESSAGE = "Malformed Metadata.";
+    private static final String NO_METADATA_MESSAGE = "Missing Metadata.";
+
+    private boolean limited = false;
+    private Random jitterGenerator;
+    private Gson metadataBuilder;
+    @NonNull
+    private EventReceiver eventReceiver;
+
+    /**
+     * @param eventReceiver receiver for any inbound events.
+     */
+    public DataRouterSubscriber(EventReceiver eventReceiver) {
+        this.eventReceiver = eventReceiver;
+        this.jitterGenerator = new Random();
+        this.metadataBuilder = new GsonBuilder().registerTypeAdapter(EventMetadata.class, new RequiredFieldDeserializer<EventMetadata>())
+                .create();
+    }
+
+    /**
+     * Starts data flow by subscribing to data router through bus controller.
+     *
+     * @param config configuration object containing bus controller endpoint for subscription and
+     *               all non constant configuration for subscription through this endpoint.
+     * @throws TooManyTriesException in the event that timeout has occurred several times.
+     */
+    public void start(BusControllerConfig config) throws TooManyTriesException, InterruptedException {
+        subscribe(NUMBER_OF_ATTEMPTS, DEFAULT_TIMEOUT, config);
+    }
+
+    private HttpURLConnection getBusControllerConnection(BusControllerConfig config, int timeout) throws IOException {
+        HttpURLConnection connection = (HttpURLConnection) config.getDataRouterSubscribeEndpoint()
+                .openConnection();
+        connection.setRequestMethod("POST");
+        connection.setConnectTimeout(timeout);
+        connection.setReadTimeout(timeout);
+        connection.setRequestProperty("Content-Type", "application/json");
+        connection.setDoOutput(true);
+        return connection;
+    }
+
+    private JsonObject getBusControllerSubscribeBody(BusControllerConfig config) {
+        JsonObject subscriberObj = new JsonObject();
+        subscriberObj.addProperty("dcaeLocationName", config.getDcaeLocation());
+        subscriberObj.addProperty("deliveryURL", config.getDeliveryURL());
+        subscriberObj.addProperty("feedId", config.getFeedId());
+        subscriberObj.addProperty("lastMod", config.getLastMod());
+        subscriberObj.addProperty("username", config.getUsername());
+        subscriberObj.addProperty("userpwd", config.getPassword());
+        return subscriberObj;
+    }
+
+    private void subscribe(int attempts, int timeout, BusControllerConfig config) throws TooManyTriesException, InterruptedException {
+        int subResponse = 504;
+        String subMessage = "";
+        try {
+            HttpURLConnection connection = getBusControllerConnection(config, timeout);
+
+            try (OutputStream bodyStream = connection.getOutputStream();
+                 OutputStreamWriter bodyWriter = new OutputStreamWriter(bodyStream, StandardCharsets.UTF_8)) {
+                bodyWriter.write(getBusControllerSubscribeBody(config).toString());
+            }
+            subResponse = connection.getResponseCode();
+            subMessage = connection.getResponseMessage();
+        } catch (IOException e) {
+            log.info("Timeout Failure:", e);
+        }
+        log.info("Request to bus controller executed with Response Code: '{}' and Response Event: '{}'.", subResponse, subMessage);
+        if (subResponse >= 300 && attempts > 1) {
+            Thread.sleep(timeout);
+            subscribe(--attempts, (timeout * 2) + jitterGenerator.nextInt(MAX_JITTER), config);
+        } else if (subResponse >= 300) {
+            throw new TooManyTriesException("Failed to subscribe within appropriate amount of attempts");
+        }
+    }
+
+    /**
+     * Receives inbound requests, verifies that required headers are valid
+     * and passes an Event onto the eventReceiver.
+     * The forwarded httpServerExchange response is the responsibility of the eventReceiver.
+     *
+     * @param httpServerExchange inbound http server exchange.
+     */
+    @Override
+    public void handleRequest(HttpServerExchange httpServerExchange) {
+        if (limited) {
+            httpServerExchange.setStatusCode(StatusCodes.SERVICE_UNAVAILABLE)
+                    .getResponseSender()
+                    .send(StatusCodes.SERVICE_UNAVAILABLE_STRING);
+        } else {
+            try {
+                String metadataAsString = Optional.of(httpServerExchange.getRequestHeaders()
+                        .get(METADATA_HEADER))
+                        .map((HeaderValues headerValues) -> headerValues.get(0))
+                        .orElseThrow(() -> new NoMetadataException("Metadata Not found"));
+
+                EventMetadata metadata = metadataBuilder.fromJson(metadataAsString, EventMetadata.class);
+                httpServerExchange.getRequestReceiver()
+                        .receiveFullString((callbackExchange, body) -> {
+                            httpServerExchange.dispatch(() -> eventReceiver.receive(new Event(callbackExchange, body, metadata)));
+                        });
+            } catch (NoMetadataException exception) {
+                log.info("Bad Request: no metadata found under '{}' header.", METADATA_HEADER, exception);
+                httpServerExchange.setStatusCode(StatusCodes.BAD_REQUEST)
+                        .getResponseSender()
+                        .send(NO_METADATA_MESSAGE);
+            } catch (JsonParseException exception) {
+                log.info("Bad Request: Failure to parse metadata", exception);
+                httpServerExchange.setStatusCode(StatusCodes.BAD_REQUEST)
+                        .getResponseSender()
+                        .send(BAD_METADATA_MESSAGE);
+            }
+        }
+    }
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/datarouter/EventReceiver.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/datarouter/EventReceiver.java
new file mode 100644
index 0000000..77c8153
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/datarouter/EventReceiver.java
@@ -0,0 +1,31 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.dcaegen2.services.pmmapper.datarouter;
+
+
+import org.onap.dcaegen2.services.pmmapper.model.Event;
+
+/**
+ * Sink for Events received from the data router subscriber.
+ */
+public interface EventReceiver {
+    void receive(Event event);
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/exceptions/NoMetadataException.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/exceptions/NoMetadataException.java
new file mode 100644
index 0000000..280b9da
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/exceptions/NoMetadataException.java
@@ -0,0 +1,27 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.dcaegen2.services.pmmapper.exceptions;
+
+public class NoMetadataException extends Exception {
+    public NoMetadataException(String errorMessage) {
+        super(errorMessage);
+    }
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/exceptions/TooManyTriesException.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/exceptions/TooManyTriesException.java
new file mode 100644
index 0000000..922239b
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/exceptions/TooManyTriesException.java
@@ -0,0 +1,29 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcaegen2.services.pmmapper.exceptions;
+
+/**
+ * Exception indicates that a task has been attempted too many times.
+ */
+public class TooManyTriesException extends Exception {
+    public TooManyTriesException(String errorMessage){
+        super(errorMessage);
+    }
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/model/Event.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/model/Event.java
new file mode 100644
index 0000000..a08dcfb
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/model/Event.java
@@ -0,0 +1,37 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcaegen2.services.pmmapper.model;
+
+import io.undertow.server.HttpServerExchange;
+import lombok.Data;
+import lombok.NonNull;
+
+/**
+ * Class used to pass around relevant inbound event data.
+ */
+@Data
+public class Event {
+    @NonNull
+    private HttpServerExchange httpServerExchange;
+    @NonNull
+    private String body;
+    @NonNull
+    private EventMetadata metadata;
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/model/EventMetadata.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/model/EventMetadata.java
new file mode 100644
index 0000000..601b00f
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/model/EventMetadata.java
@@ -0,0 +1,50 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcaegen2.services.pmmapper.model;
+
+import lombok.Data;
+import org.onap.dcaegen2.services.pmmapper.utils.GSONRequired;
+
+/**
+ * Metadata for inbound event onto data router subscriber.
+ */
+@Data
+public class EventMetadata {
+    @GSONRequired
+    private String productName;
+    @GSONRequired
+    private String vendorName;
+    @GSONRequired
+    private String startEpochMicrosec;
+    @GSONRequired
+    private String lastEpochMicrosec;
+    @GSONRequired
+    private String sourceName;
+    @GSONRequired
+    private String timeZoneOffset;
+    @GSONRequired
+    private String location;
+    @GSONRequired
+    private String compression;
+    @GSONRequired
+    private String fileFormatType;
+    @GSONRequired
+    private String fileFormatVersion;
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/utils/GSONRequired.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/utils/GSONRequired.java
new file mode 100644
index 0000000..a6ce7b9
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/utils/GSONRequired.java
@@ -0,0 +1,33 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcaegen2.services.pmmapper.utils;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation used to make a field required for Gson.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.FIELD)
+public @interface GSONRequired {
+}
diff --git a/src/main/java/org/onap/dcaegen2/services/pmmapper/utils/RequiredFieldDeserializer.java b/src/main/java/org/onap/dcaegen2/services/pmmapper/utils/RequiredFieldDeserializer.java
new file mode 100644
index 0000000..e956398
--- /dev/null
+++ b/src/main/java/org/onap/dcaegen2/services/pmmapper/utils/RequiredFieldDeserializer.java
@@ -0,0 +1,57 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2019 Nordix Foundation.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcaegen2.services.pmmapper.utils;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParseException;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Type;
+
+
+/**
+ * Extension of the default deserializer with support for GSONRequired annotation.
+ * @param <T> Type of object for deserialization process.
+ */
+public class RequiredFieldDeserializer<T> implements JsonDeserializer<T> {
+
+    @Override
+    public T deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
+        T obj = new Gson().fromJson(jsonElement, type);
+        for (Field field : obj.getClass().getDeclaredFields()) {
+            if (field.getAnnotation(GSONRequired.class) != null) {
+                field.setAccessible(true);
+                try {
+                    if (field.get(obj) == null) {
+                        throw new JsonParseException(String.format("Field: '%s', is required but not found.", field.getName()));
+                    }
+                } catch (Exception exception) {
+                    throw new JsonParseException("Failed to check fields.", exception);
+                }
+            }
+        }
+
+        return obj;
+    }
+
+}