Complex classes like Payload often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Payload, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 32 | class Payload implements \JsonSerializable  | 
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| 33 | { | 
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| 34 | const PAYLOAD_ROOT_KEY = 'aps';  | 
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| 35 | const PAYLOAD_ALERT_KEY = 'alert';  | 
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| 36 | const PAYLOAD_BADGE_KEY = 'badge';  | 
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| 37 | const PAYLOAD_SOUND_KEY = 'sound';  | 
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| 38 | const PAYLOAD_CONTENT_AVAILABLE_KEY = 'content-available';  | 
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| 39 | const PAYLOAD_MUTABLE_CONTENT_KEY = 'mutable-content';  | 
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| 40 | const PAYLOAD_CATEGORY_KEY = 'category';  | 
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| 41 | const PAYLOAD_THREAD_ID_KEY = 'thread-id';  | 
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| 42 | const PAYLOAD_URL_ARGS_KEY = 'url-args';  | 
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| 43 | |||
| 44 | const PAYLOAD_HTTP2_REGULAR_NOTIFICATION_MAXIMUM_SIZE = 4096;  | 
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| 45 | const PAYLOAD_HTTP2_VOIP_NOTIFICATION_MAXIMUM_SIZE = 5120;  | 
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| 46 | const PAYLOAD_BINARY_REGULAR_NOTIFICATION_MAXIMUM_SIZE = 2048;  | 
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| 47 | |||
| 48 | /**  | 
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| 49 | * The notification settings for your app on the user’s device determine whether an alert or banner is displayed.  | 
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| 50 | *  | 
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| 51 | * @var Alert|string  | 
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| 52 | */  | 
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| 53 | private $alert;  | 
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| 54 | |||
| 55 | /**  | 
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| 56 | * The number to display as the badge of the app icon.  | 
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| 57 | * If this property is absent, the badge is not changed.  | 
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| 58 | *  | 
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| 59 | * @var int  | 
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| 60 | */  | 
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| 61 | private $badge;  | 
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| 62 | |||
| 63 | /**  | 
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| 64 | * The name of a sound file in the app bundle or in the Library/Sounds folder of the app’s data container.  | 
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| 65 | *  | 
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| 66 | * @var string  | 
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| 67 | */  | 
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| 68 | private $sound;  | 
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| 69 | |||
| 70 | /**  | 
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| 71 | * Include this key with a value of true to configure a silent notification.  | 
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| 72 | *  | 
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| 73 | * @var bool  | 
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| 74 | */  | 
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| 75 | private $contentAvailable;  | 
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| 76 | |||
| 77 | /**  | 
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| 78 | * Include this key with a value of true to configure a mutable content notification.  | 
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| 79 | *  | 
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| 80 | * @var bool  | 
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| 81 | */  | 
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| 82 | private $mutableContent;  | 
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| 83 | |||
| 84 | /**  | 
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| 85 | * Provide this key with a string value that represents the notification’s type.  | 
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| 86 | *  | 
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| 87 | * @var string  | 
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| 88 | */  | 
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| 89 | private $category;  | 
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| 90 | |||
| 91 | /**  | 
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| 92 | * Provide this key with a string value that represents the app-specific identifier for grouping notifications.  | 
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| 93 | *  | 
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| 94 | * @var string  | 
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| 95 | */  | 
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| 96 | private $threadId;  | 
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| 97 | |||
| 98 | /**  | 
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| 99 | * Provide this key with an array value that represents the url-args for Safari notifications.  | 
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| 100 | *  | 
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| 101 | * @var string  | 
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| 102 | */  | 
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| 103 | private $urlArgs;  | 
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| 104 | |||
| 105 | /**  | 
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| 106 | * Payload custom values.  | 
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| 107 | *  | 
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| 108 | * @var array  | 
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| 109 | */  | 
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| 110 | private $customValues;  | 
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| 111 | |||
| 112 | /**  | 
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| 113 | * Push notification type  | 
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| 114 | *  | 
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| 115 | * https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/sending_notification_requests_to_apns#2947607  | 
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| 116 | *  | 
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| 117 | * @var string  | 
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| 118 | */  | 
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| 119 | private $pushType;  | 
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| 120 | |||
| 121 | protected function __construct()  | 
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| 124 | |||
| 125 | /**  | 
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| 126 | * @return Payload  | 
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| 127 | */  | 
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| 128 | public static function create(): Payload  | 
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| 132 | |||
| 133 | /**  | 
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| 134 | * Get Alert.  | 
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| 135 | *  | 
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| 136 | * @return Alert|null  | 
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| 137 | */  | 
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| 138 | public function getAlert()  | 
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| 142 | |||
| 143 | /**  | 
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| 144 | * Set Alert.  | 
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| 145 | *  | 
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| 146 | * @param Alert|string $alert  | 
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| 147 | *  | 
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| 148 | * @return Payload  | 
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| 149 | */  | 
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| 150 | public function setAlert($alert): Payload  | 
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| 158 | |||
| 159 | /**  | 
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| 160 | * Get badge.  | 
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| 161 | *  | 
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| 162 | * @return int|null  | 
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| 163 | */  | 
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| 164 | public function getBadge()  | 
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| 168 | |||
| 169 | /**  | 
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| 170 | * Set badge.  | 
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| 171 | *  | 
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| 172 | * @param int $value  | 
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| 173 | *  | 
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| 174 | * @return Payload  | 
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| 175 | */  | 
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| 176 | public function setBadge(int $value): Payload  | 
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| 182 | |||
| 183 | /**  | 
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| 184 | * Get sound.  | 
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| 185 | *  | 
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| 186 | * @return string|null  | 
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| 187 | */  | 
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| 188 | public function getSound()  | 
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| 192 | |||
| 193 | /**  | 
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| 194 | * Set sound.  | 
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| 195 | *  | 
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| 196 | * @param string $value  | 
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| 197 | *  | 
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| 198 | * @return Payload  | 
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| 199 | */  | 
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| 200 | public function setSound(string $value): Payload  | 
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| 206 | |||
| 207 | /**  | 
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| 208 | * Set content availability.  | 
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| 209 | *  | 
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| 210 | * @param bool $value  | 
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| 211 | *  | 
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| 212 | * @return Payload  | 
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| 213 | */  | 
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| 214 | public function setContentAvailability(bool $value): Payload  | 
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| 220 | |||
| 221 | /**  | 
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| 222 | * Get content availability.  | 
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| 223 | *  | 
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| 224 | * @return bool|null  | 
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| 225 | */  | 
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| 226 | public function isContentAvailable()  | 
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| 230 | |||
| 231 | /**  | 
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| 232 | * Set the mutable-content key for Notification Service Extensions on iOS10.  | 
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| 233 | *  | 
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| 234 | * @see http://bit.ly/mutable-content  | 
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| 235 | *  | 
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| 236 | * @param bool $value  | 
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| 237 | *  | 
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| 238 | * @return Payload  | 
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| 239 | */  | 
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| 240 | public function setMutableContent(bool $value): Payload  | 
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| 246 | |||
| 247 | /**  | 
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| 248 | * Is content mutable.  | 
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| 249 | *  | 
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| 250 | * @return bool|null  | 
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| 251 | */  | 
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| 252 | public function hasMutableContent()  | 
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| 256 | |||
| 257 | /**  | 
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| 258 | * Get category.  | 
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| 259 | *  | 
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| 260 | * @return string|null  | 
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| 261 | */  | 
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| 262 | public function getCategory()  | 
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| 266 | |||
| 267 | /**  | 
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| 268 | * Set category.  | 
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| 269 | *  | 
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| 270 | * @param string $value  | 
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| 271 | *  | 
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| 272 | * @return Payload  | 
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| 273 | */  | 
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| 274 | public function setCategory(string $value): Payload  | 
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| 280 | |||
| 281 | /**  | 
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| 282 | * Get thread-id.  | 
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| 283 | *  | 
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| 284 | * @return string|null  | 
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| 285 | */  | 
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| 286 | public function getThreadId()  | 
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| 290 | |||
| 291 | /**  | 
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| 292 | * Set thread-id.  | 
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| 293 | *  | 
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| 294 | * @param string $value  | 
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| 295 | *  | 
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| 296 | * @return Payload  | 
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| 297 | */  | 
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| 298 | public function setThreadId(string $value): Payload  | 
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| 304 | |||
| 305 | /**  | 
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| 306 | * Get url-args.  | 
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| 307 | *  | 
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| 308 | * @return array|null  | 
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| 309 | */  | 
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| 310 | public function getUrlArgs()  | 
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| 314 | |||
| 315 | /**  | 
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| 316 | * Set url-args.  | 
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| 317 | *  | 
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| 318 | * @param array $value  | 
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| 319 | *  | 
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| 320 | * @return Payload  | 
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| 321 | */  | 
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| 322 | public function setUrlArgs(array $value): Payload  | 
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| 328 | |||
| 329 | /**  | 
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| 330 | * Set custom value for Payload.  | 
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| 331 | *  | 
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| 332 | * @param string $key  | 
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| 333 | * @param mixed $value  | 
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| 334 | *  | 
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| 335 | * @return Payload  | 
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| 336 | * @throws InvalidPayloadException  | 
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| 337 | */  | 
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| 338 | public function setCustomValue(string $key, $value): Payload  | 
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| 348 | |||
| 349 | /**  | 
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| 350 | * Get custom value.  | 
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| 351 | *  | 
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| 352 | * @param $key  | 
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| 353 | *  | 
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| 354 | * @return mixed  | 
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| 355 | * @throws InvalidPayloadException  | 
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| 356 | */  | 
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| 357 | public function getCustomValue($key)  | 
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| 365 | |||
| 366 | /**  | 
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| 367 | * Set push type for Payload.  | 
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| 368 | *  | 
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| 369 | * @param string $pushType  | 
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| 370 | * @return Payload  | 
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| 371 | */  | 
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| 372 |     public function setPushType($pushType) { | 
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| 377 | |||
| 378 | /**  | 
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| 379 | * Get push type for Payload.  | 
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| 380 | *  | 
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| 381 | * @return string  | 
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| 382 | */  | 
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| 383 |     public function getPushType() { | 
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| 386 | |||
| 387 | /**  | 
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| 388 | * Convert Payload to JSON.  | 
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| 389 | *  | 
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| 390 | * @return string  | 
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| 391 | */  | 
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| 392 | public function toJson(): string  | 
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| 396 | |||
| 397 | /**  | 
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| 398 | * Specify data which should be serialized to JSON.  | 
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| 399 | *  | 
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| 400 | * @return array  | 
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| 401 | * @link http://php.net/manual/en/jsonserializable.jsonserialize.php  | 
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| 402 | */  | 
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| 403 | public function jsonSerialize()  | 
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| 445 | |||
| 446 | /**  | 
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| 447 | * Get default payload structure.  | 
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| 448 | *  | 
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| 449 | * @return array  | 
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| 450 | */  | 
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| 451 | private static function getDefaultPayloadStructure()  | 
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| 455 | }  | 
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| 456 | 
Our type inference engine has found an assignment to a property that is incompatible with the declared type of that property.
Either this assignment is in error or the assigned type should be added to the documentation/type hint for that property..