Complex classes like Subscription 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 Subscription, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 11 | class Subscription implements SubscriptionInterface  | 
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| 12 | { | 
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| 13 | use TimestampableTrait;  | 
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| 14 | |||
| 15 | /**  | 
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| 16 | * @var mixed  | 
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| 17 | */  | 
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| 18 | protected $id;  | 
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| 19 | |||
| 20 | /**  | 
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| 21 | * @var int  | 
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| 22 | */  | 
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| 23 | protected $amount;  | 
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| 24 | |||
| 25 | /**  | 
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| 26 | * @var string|null  | 
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| 27 | */  | 
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| 28 | protected $number;  | 
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| 29 | |||
| 30 | /**  | 
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| 31 | * @var string  | 
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| 32 | */  | 
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| 33 | protected $currencyCode;  | 
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| 34 | |||
| 35 | /**  | 
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| 36 | * @var string|null  | 
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| 37 | */  | 
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| 38 | protected $interval;  | 
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| 39 | |||
| 40 | /**  | 
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| 41 | * @var \DateTimeInterface|null  | 
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| 42 | */  | 
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| 43 | protected $startDate;  | 
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| 44 | |||
| 45 | /**  | 
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| 46 | * @var string|null  | 
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| 47 | */  | 
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| 48 | protected $type = SubscriptionInterface::TYPE_NON_RECURRING;  | 
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| 49 | |||
| 50 | /**  | 
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| 51 | * @var Collection|SubscriptionItemInterface[]  | 
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| 52 | */  | 
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| 53 | protected $items;  | 
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| 54 | |||
| 55 | /**  | 
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| 56 | * @var \DateTimeInterface|null  | 
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| 57 | */  | 
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| 58 | protected $purchaseCompletedAt;  | 
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| 59 | |||
| 60 | /**  | 
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| 61 | * @var int  | 
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| 62 | */  | 
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| 63 | protected $itemsTotal = 0;  | 
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| 64 | |||
| 65 | /**  | 
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| 66 | * @var int  | 
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| 67 | */  | 
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| 68 | protected $total = 0;  | 
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| 69 | |||
| 70 | /**  | 
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| 71 | * @var string  | 
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| 72 | */  | 
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| 73 | protected $state = SubscriptionInterface::STATE_NEW;  | 
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| 74 | |||
| 75 | /**  | 
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| 76 | * @var Collection|MetadataInterface[]  | 
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| 77 | */  | 
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| 78 | protected $metadata;  | 
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| 79 | |||
| 80 | /**  | 
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| 81 | * Subscription constructor.  | 
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| 82 | */  | 
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| 83 | public function __construct()  | 
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| 89 | |||
| 90 | /**  | 
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| 91 |      * {@inheritdoc} | 
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| 92 | */  | 
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| 93 | public function getId()  | 
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| 97 | |||
| 98 | /**  | 
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| 99 |      * {@inheritdoc} | 
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| 100 | */  | 
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| 101 | public function getAmount(): ?int  | 
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| 105 | |||
| 106 | /**  | 
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| 107 |      * {@inheritdoc} | 
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| 108 | */  | 
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| 109 | public function setAmount(int $amount): void  | 
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| 113 | |||
| 114 | /**  | 
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| 115 |      * {@inheritdoc} | 
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| 116 | */  | 
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| 117 | public function getCurrencyCode(): ?string  | 
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| 121 | |||
| 122 | /**  | 
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| 123 |      * {@inheritdoc} | 
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| 124 | */  | 
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| 125 | public function setCurrencyCode(string $currencyCode)  | 
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| 129 | |||
| 130 | /**  | 
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| 131 |      * {@inheritdoc} | 
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| 132 | */  | 
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| 133 | public function getInterval(): ?string  | 
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| 137 | |||
| 138 | /**  | 
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| 139 |      * {@inheritdoc} | 
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| 140 | */  | 
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| 141 | public function setInterval(?string $interval)  | 
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| 145 | |||
| 146 | /**  | 
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| 147 |      * {@inheritdoc} | 
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| 148 | */  | 
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| 149 | public function getStartDate(): ?\DateTimeInterface  | 
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| 153 | |||
| 154 | /**  | 
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| 155 |      * {@inheritdoc} | 
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| 156 | */  | 
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| 157 | public function setStartDate(?\DateTimeInterface $startDate): void  | 
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| 161 | |||
| 162 | /**  | 
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| 163 |      * {@inheritdoc} | 
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| 164 | */  | 
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| 165 | public function getType(): ?string  | 
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| 169 | |||
| 170 | /**  | 
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| 171 |      * {@inheritdoc} | 
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| 172 | */  | 
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| 173 | public function setType(?string $type): void  | 
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| 177 | |||
| 178 | /**  | 
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| 179 |      * {@inheritdoc} | 
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| 180 | */  | 
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| 181 | public function getPurchaseCompletedAt(): ?\DateTimeInterface  | 
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| 185 | |||
| 186 | /**  | 
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| 187 |      * {@inheritdoc} | 
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| 188 | */  | 
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| 189 | public function setPurchaseCompletedAt(?\DateTimeInterface $purchaseCompletedAt): void  | 
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| 193 | |||
| 194 | /**  | 
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| 195 |      * {@inheritdoc} | 
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| 196 | */  | 
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| 197 | public function completePurchase(): void  | 
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| 201 | |||
| 202 | /**  | 
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| 203 |      * {@inheritdoc} | 
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| 204 | */  | 
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| 205 | public function getItems(): Collection  | 
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| 209 | |||
| 210 | /**  | 
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| 211 |      * {@inheritdoc} | 
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| 212 | */  | 
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| 213 | public function clearItems(): void  | 
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| 219 | |||
| 220 | /**  | 
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| 221 |      * {@inheritdoc} | 
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| 222 | */  | 
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| 223 | public function countItems(): int  | 
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| 227 | |||
| 228 | /**  | 
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| 229 |      * {@inheritdoc} | 
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| 230 | */  | 
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| 231 | public function addItem(SubscriptionItemInterface $item): void  | 
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| 241 | |||
| 242 | /**  | 
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| 243 |      * {@inheritdoc} | 
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| 244 | */  | 
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| 245 | public function removeItem(SubscriptionItemInterface $item): void  | 
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| 253 | |||
| 254 | /**  | 
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| 255 |      * {@inheritdoc} | 
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| 256 | */  | 
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| 257 | public function hasItem(SubscriptionItemInterface $item): bool  | 
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| 261 | |||
| 262 | /**  | 
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| 263 |      * {@inheritdoc} | 
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| 264 | */  | 
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| 265 | public function getItemsTotal(): int  | 
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| 269 | |||
| 270 | /**  | 
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| 271 |      * {@inheritdoc} | 
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| 272 | */  | 
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| 273 | public function recalculateItemsTotal(): void  | 
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| 282 | |||
| 283 | /**  | 
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| 284 |      * {@inheritdoc} | 
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| 285 | */  | 
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| 286 | protected function recalculateTotal(): void  | 
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| 294 | |||
| 295 | /**  | 
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| 296 |      * {@inheritdoc} | 
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| 297 | */  | 
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| 298 | public function getTotal(): int  | 
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| 302 | |||
| 303 | /**  | 
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| 304 |      * {@inheritdoc} | 
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| 305 | */  | 
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| 306 | public function getTotalQuantity(): int  | 
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| 316 | |||
| 317 | /**  | 
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| 318 |      * {@inheritdoc} | 
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| 319 | */  | 
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| 320 | public function isEmpty(): bool  | 
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| 324 | |||
| 325 | /**  | 
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| 326 |      * {@inheritdoc} | 
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| 327 | */  | 
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| 328 | public function getState(): string  | 
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| 332 | |||
| 333 | /**  | 
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| 334 |      * {@inheritdoc} | 
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| 335 | */  | 
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| 336 | public function setState(string $state): void  | 
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| 340 | |||
| 341 | /**  | 
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| 342 |      * {@inheritdoc} | 
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| 343 | */  | 
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| 344 | public function getMetadata(): Collection  | 
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| 348 | |||
| 349 | /**  | 
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| 350 |      * {@inheritdoc} | 
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| 351 | */  | 
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| 352 | public function setMetadata(Collection $metadata): void  | 
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| 360 | |||
| 361 | /**  | 
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| 362 |      * {@inheritdoc} | 
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| 363 | */  | 
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| 364 | public function hasMetadata(): bool  | 
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| 368 | |||
| 369 | /**  | 
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| 370 |      * {@inheritdoc} | 
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| 371 | */  | 
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| 372 | public function addMetadata(MetadataInterface $metadata): void  | 
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| 380 | |||
| 381 | /**  | 
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| 382 |      * {@inheritdoc} | 
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| 383 | */  | 
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| 384 | public function removeMetadata(MetadataInterface $metadata): void  | 
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| 392 | |||
| 393 | /**  | 
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| 394 |      * {@inheritdoc} | 
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| 395 | */  | 
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| 396 | public function hasSingleMetadata(MetadataInterface $metadata): bool  | 
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| 400 | }  | 
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| 401 |