Add @Nullable annotations to Task fields

import android.app.TaskInfo;

import android.content.ComponentName;

import android.content.Intent;

import android.content.pm.ActivityInfo;

import android.graphics.Color;

import android.graphics.drawable.Drawable;

import android.os.Parcel;

import android.os.Parcelable;

import android.view.ViewDebug;

import com.android.systemui.shared.recents.utilities.Utilities;

import androidx.annotation.Nullable;

import java.io.PrintWriter;

import java.util.ArrayList;

import java.util.Objects;

/**

     * The icon is the task description icon (if provided), which falls back to the activity icon,

     * which can then fall back to the application icon.

     */

    public Drawable icon;

    public ThumbnailData thumbnail;

    @Nullable public Drawable icon;

    @Nullable public ThumbnailData thumbnail;

    @ViewDebug.ExportedProperty(category="recents")

    @Deprecated

    public String title;