// ------------------------------------------------------------------------------
// Copyright (c) 2017 Microsoft Corporation
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sub-license, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
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// THE SOFTWARE.
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package com.microsoft.graph.serializer;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import javax.annotation.Nullable;
import javax.annotation.Nonnull;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.JsonParser;
import com.google.common.reflect.TypeToken;
import com.microsoft.graph.http.BaseCollectionPage;
import com.microsoft.graph.http.BaseRequestBuilder;
import com.microsoft.graph.http.IRequestBuilder;
import com.microsoft.graph.logger.ILogger;

/** Specialized serializer to handle collection pages */
public class CollectionPageSerializer {

	private static DefaultSerializer serializer;
	/** length of the word "page" */
	private final static Integer pageLength = 4;
	/** length of the word "collection" */
	private final static Integer collectionLength = 10;
	/** length of the work "response" */
	private final static Integer responseLength = 8;

	/**
	 * Not available for instantiation
	 */
	private CollectionPageSerializer() {
	}

	/**
     * Serializes an CollectionPage
     *
     * @param src the CollectionPage variable for serialization
     * @param logger the logger
	 * @param <T1> the entity type for the collection
	 * @param <T2> the collection request builder interface type
     * @return       JsonElement of CollectionPage
     */
	@Nullable
	public static <T1, T2 extends BaseRequestBuilder<T1>> JsonElement serialize(@Nonnull final BaseCollectionPage<T1, T2> src, @Nonnull final ILogger logger) {
		if(src == null) {
			return null;
		}
		JsonArray jsonArray = new JsonArray();
		List<T1> items = src.getCurrentPage();
		serializer = new DefaultSerializer(logger);
		for(T1 item : items) {
			final String json = serializer.serializeObject(item);
			final JsonElement element = JsonParser.parseString(json);
			if(element != null && element.isJsonObject()) {
				final JsonObject jsonObject = element.getAsJsonObject();
				jsonArray.add(jsonObject);
			}
		}
		return jsonArray;
	}

	/**
     * Deserializes the JsonElement
     *
     * @param json the source CollectionPage's Json
   	 * @param typeOfT The type of the CollectionPage to deserialize to
     * @param logger the logger
	 * @param <T1> the entity type for the collection
	 * @param <T2> the collection request builder interface type
     * @throws JsonParseException the parse exception
     * @return    the deserialized CollectionPage
     */
	@SuppressWarnings("unchecked")
	@Nullable
	public static <T1, T2 extends BaseRequestBuilder<T1>> BaseCollectionPage<T1, T2> deserialize(@Nonnull final JsonElement json, @Nonnull final Type typeOfT, @Nonnull final ILogger logger) throws JsonParseException {
		if (json == null || !json.isJsonArray() || !typeOfT.getClass().equals(Class.class)) {
			return null;
		}
		serializer = new DefaultSerializer(logger);
		final JsonArray sourceArray = json.getAsJsonArray();
		final ArrayList<T1> list = new ArrayList<>(sourceArray.size());
		/** eg: com.microsoft.graph.requests.AttachmentCollectionPage */
		final String collectionPageClassCanonicalName = ((Class<?>)typeOfT).getName();
		/** eg: com.microsoft.graph.models.Attachment */
		final String baseEntityClassCanonicalName = collectionPageClassCanonicalName
					.substring(0, collectionPageClassCanonicalName.length() - pageLength - collectionLength)
					.replace("requests", "models");
		try {
			final Class<?> baseEntityClass = Class.forName(baseEntityClassCanonicalName);
			for (JsonElement sourceElement : sourceArray) {
				if (sourceElement.isJsonObject()) {
					final JsonObject sourceObject = sourceElement.getAsJsonObject();
					Class<?> entityClass = serializer.getDerivedClass(sourceObject, baseEntityClass);
					if (entityClass == null)
						entityClass = baseEntityClass;
					final T1 targetObject = (T1) serializer.deserializeObject(sourceObject, entityClass, null);
					((IJsonBackedObject) targetObject).setRawObject(serializer, sourceObject);
					list.add(targetObject);
				}
			}
			/** eg: com.microsoft.graph.requests.AttachmentCollectionResponse */
			final String responseClassCanonicalName = collectionPageClassCanonicalName
						.substring(0, collectionPageClassCanonicalName.length() - pageLength) + "Response";
			final Class<?> responseClass = Class.forName(responseClassCanonicalName);
			final Object response = responseClass.getConstructor().newInstance();
			responseClass.getField("value").set(response, list);
			final Class<?> collectionPageClass = Class.forName(collectionPageClassCanonicalName);
			/** eg: com.microsoft.graph.requests.AttachmentCollectionRequestBuilder */
			final String responseBuilderCanonicalName = responseClassCanonicalName
						.substring(0, responseClassCanonicalName.length() - responseLength) + "RequestBuilder";
			final Class<?> responseBuilderClass = Class.forName(responseBuilderCanonicalName);
			return (BaseCollectionPage<T1, T2>)collectionPageClass.getConstructor(responseClass, responseBuilderClass).newInstance(response, null);
		} catch(ClassNotFoundException ex) {
			logger.logError("Could not find class during deserialization", ex);
		} catch(NoSuchMethodException | InstantiationException | InvocationTargetException ex) {
			logger.logError("Could not instanciate type during deserialization", ex);
		} catch(NoSuchFieldException | IllegalAccessException ex) {
			logger.logError("Unable to set field value during deserialization", ex);
		}
		return null;
	}
}

@@ -5298,22 +5298,16 @@
 ityClass
-, null
 );%0A%09%09%09%09%09

Update src/main/java/com/microsoft/graph/serializer/CollectionPageSerializer.java