Complex classes like LineItem 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 LineItem, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 16 | class LineItem extends Model  | 
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| 17 | { | 
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| 18 | /**  | 
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| 19 | * @var int  | 
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| 20 | */  | 
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| 21 | protected $fulfillableQuantity;  | 
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| 22 | |||
| 23 | /**  | 
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| 24 | * @var string  | 
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| 25 | */  | 
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| 26 | protected $fulfillmentService;  | 
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| 27 | |||
| 28 | /**  | 
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| 29 | * @var string  | 
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| 30 | */  | 
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| 31 | protected $fulfillmentStatus;  | 
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| 32 | |||
| 33 | /**  | 
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| 34 | * @var int  | 
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| 35 | */  | 
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| 36 | protected $grams;  | 
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| 37 | |||
| 38 | /**  | 
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| 39 | * @var float  | 
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| 40 | */  | 
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| 41 | protected $price;  | 
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| 42 | |||
| 43 | /**  | 
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| 44 | * @var int  | 
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| 45 | */  | 
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| 46 | protected $productId;  | 
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| 47 | |||
| 48 | /**  | 
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| 49 | * @var int  | 
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| 50 | */  | 
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| 51 | protected $quantity;  | 
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| 52 | |||
| 53 | /**  | 
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| 54 | * @var bool  | 
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| 55 | */  | 
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| 56 | protected $requiresShipping;  | 
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| 57 | |||
| 58 | /**  | 
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| 59 | * @var string  | 
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| 60 | */  | 
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| 61 | protected $sku;  | 
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| 62 | |||
| 63 | /**  | 
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| 64 | * @var string  | 
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| 65 | */  | 
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| 66 | protected $title;  | 
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| 67 | |||
| 68 | /**  | 
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| 69 | * @var int  | 
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| 70 | */  | 
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| 71 | protected $variantId;  | 
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| 72 | |||
| 73 | /**  | 
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| 74 | * @var string  | 
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| 75 | */  | 
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| 76 | protected $variantTitle;  | 
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| 77 | |||
| 78 | /**  | 
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| 79 | * @var string  | 
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| 80 | */  | 
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| 81 | protected $vendor;  | 
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| 82 | |||
| 83 | /**  | 
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| 84 | * @var string  | 
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| 85 | */  | 
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| 86 | protected $name;  | 
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| 87 | |||
| 88 | /**  | 
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| 89 | * @var bool  | 
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| 90 | */  | 
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| 91 | protected $giftCard;  | 
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| 92 | |||
| 93 | /**  | 
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| 94 | * @var array  | 
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| 95 | */  | 
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| 96 | protected $properties;  | 
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| 97 | |||
| 98 | /**  | 
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| 99 | * @var bool  | 
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| 100 | */  | 
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| 101 | protected $taxable;  | 
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| 102 | |||
| 103 | /**  | 
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| 104 | * @var TaxLine[]  | 
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| 105 | */  | 
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| 106 | protected $taxLines;  | 
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| 107 | |||
| 108 | /**  | 
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| 109 | * @var float  | 
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| 110 | */  | 
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| 111 | protected $totalDiscount;  | 
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| 112 | |||
| 113 | /**  | 
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| 114 | * @var DiscountAllocation[]  | 
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| 115 | */  | 
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| 116 | protected $discountAllocations;  | 
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| 117 | |||
| 118 | /**  | 
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| 119 | * @return int  | 
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| 120 | */  | 
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| 121 | public function getFulfillableQuantity()  | 
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| 125 | |||
| 126 | /**  | 
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| 127 | * @param int $fulfillableQuantity  | 
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| 128 | *  | 
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| 129 | * @return LineItem  | 
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| 130 | */  | 
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| 131 | public function setFulfillableQuantity($fulfillableQuantity)  | 
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| 137 | |||
| 138 | /**  | 
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| 139 | * @return string  | 
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| 140 | */  | 
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| 141 | public function getFulfillmentService()  | 
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| 145 | |||
| 146 | /**  | 
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| 147 | * @param string $fulfillmentService  | 
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| 148 | *  | 
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| 149 | * @return LineItem  | 
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| 150 | */  | 
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| 151 | public function setFulfillmentService($fulfillmentService)  | 
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| 157 | |||
| 158 | /**  | 
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| 159 | * @return string  | 
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| 160 | */  | 
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| 161 | public function getFulfillmentStatus()  | 
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| 165 | |||
| 166 | /**  | 
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| 167 | * @param string $fulfillmentStatus  | 
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| 168 | *  | 
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| 169 | * @return LineItem  | 
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| 170 | */  | 
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| 171 | public function setFulfillmentStatus($fulfillmentStatus)  | 
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| 177 | |||
| 178 | /**  | 
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| 179 | * @return int  | 
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| 180 | */  | 
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| 181 | public function getGrams()  | 
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| 185 | |||
| 186 | /**  | 
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| 187 | * @param int $grams  | 
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| 188 | *  | 
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| 189 | * @return LineItem  | 
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| 190 | */  | 
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| 191 | public function setGrams($grams)  | 
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| 197 | |||
| 198 | /**  | 
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| 199 | * @return double  | 
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| 200 | */  | 
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| 201 | public function getPrice()  | 
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| 205 | |||
| 206 | /**  | 
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| 207 | * @param string $price  | 
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| 208 | *  | 
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| 209 | * @return LineItem  | 
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| 210 | */  | 
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| 211 | public function setPrice($price)  | 
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| 217 | |||
| 218 | /**  | 
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| 219 | * @return int  | 
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| 220 | */  | 
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| 221 | public function getProductId()  | 
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| 225 | |||
| 226 | /**  | 
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| 227 | * @param int $productId  | 
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| 228 | *  | 
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| 229 | * @return LineItem  | 
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| 230 | */  | 
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| 231 | public function setProductId($productId)  | 
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| 237 | |||
| 238 | /**  | 
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| 239 | * @return int  | 
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| 240 | */  | 
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| 241 | public function getQuantity()  | 
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| 245 | |||
| 246 | /**  | 
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| 247 | * @param int $quantity  | 
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| 248 | *  | 
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| 249 | * @return LineItem  | 
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| 250 | */  | 
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| 251 | public function setQuantity($quantity)  | 
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| 257 | |||
| 258 | /**  | 
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| 259 | * @return bool  | 
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| 260 | */  | 
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| 261 | public function isRequiresShipping()  | 
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| 265 | |||
| 266 | /**  | 
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| 267 | * @param bool $requiresShipping  | 
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| 268 | *  | 
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| 269 | * @return LineItem  | 
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| 270 | */  | 
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| 271 | public function setRequiresShipping($requiresShipping)  | 
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| 277 | |||
| 278 | /**  | 
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| 279 | * @return string  | 
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| 280 | */  | 
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| 281 | public function getSku()  | 
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| 285 | |||
| 286 | /**  | 
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| 287 | * @param string $sku  | 
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| 288 | *  | 
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| 289 | * @return LineItem  | 
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| 290 | */  | 
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| 291 | public function setSku($sku)  | 
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| 297 | |||
| 298 | /**  | 
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| 299 | * @return string  | 
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| 300 | */  | 
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| 301 | public function getTitle()  | 
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| 302 |     { | 
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| 303 | return $this->title;  | 
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| 304 | }  | 
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| 305 | |||
| 306 | /**  | 
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| 307 | * @param string $title  | 
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| 308 | *  | 
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| 309 | * @return LineItem  | 
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| 310 | */  | 
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| 311 | public function setTitle($title)  | 
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| 317 | |||
| 318 | /**  | 
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| 319 | * @return int  | 
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| 320 | */  | 
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| 321 | public function getVariantId()  | 
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| 325 | |||
| 326 | /**  | 
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| 327 | * @param int $variantId  | 
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| 328 | *  | 
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| 329 | * @return LineItem  | 
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| 330 | */  | 
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| 331 | public function setVariantId($variantId)  | 
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| 337 | |||
| 338 | /**  | 
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| 339 | * @return string  | 
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| 340 | */  | 
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| 341 | public function getVariantTitle()  | 
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| 345 | |||
| 346 | /**  | 
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| 347 | * @param string $variantTitle  | 
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| 348 | *  | 
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| 349 | * @return LineItem  | 
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| 350 | */  | 
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| 351 | public function setVariantTitle($variantTitle)  | 
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| 357 | |||
| 358 | /**  | 
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| 359 | * @return string  | 
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| 360 | */  | 
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| 361 | public function getVendor()  | 
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| 365 | |||
| 366 | /**  | 
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| 367 | * @param string $vendor  | 
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| 368 | *  | 
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| 369 | * @return LineItem  | 
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| 370 | */  | 
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| 371 | public function setVendor($vendor)  | 
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| 377 | |||
| 378 | /**  | 
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| 379 | * @return string  | 
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| 380 | */  | 
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| 381 | public function getName()  | 
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| 385 | |||
| 386 | /**  | 
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| 387 | * @param string $name  | 
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| 388 | *  | 
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| 389 | * @return LineItem  | 
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| 390 | */  | 
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| 391 | public function setName($name)  | 
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| 397 | |||
| 398 | /**  | 
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| 399 | * @return bool  | 
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| 400 | */  | 
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| 401 | public function isGiftCard()  | 
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| 405 | |||
| 406 | /**  | 
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| 407 | * @param bool $giftCard  | 
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| 408 | *  | 
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| 409 | * @return LineItem  | 
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| 410 | */  | 
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| 411 | public function setGiftCard($giftCard)  | 
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| 417 | |||
| 418 | /**  | 
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| 419 | * @return array  | 
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| 420 | */  | 
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| 421 | public function getProperties()  | 
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| 425 | |||
| 426 | /**  | 
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| 427 | * @param array $properties  | 
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| 428 | *  | 
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| 429 | * @return LineItem  | 
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| 430 | */  | 
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| 431 | public function setProperties($properties)  | 
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| 437 | |||
| 438 | /**  | 
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| 439 | * @return bool  | 
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| 440 | */  | 
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| 441 | public function isTaxable()  | 
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| 445 | |||
| 446 | /**  | 
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| 447 | * @param bool $taxable  | 
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| 448 | *  | 
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| 449 | * @return LineItem  | 
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| 450 | */  | 
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| 451 | public function setTaxable($taxable)  | 
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| 457 | |||
| 458 | /**  | 
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| 459 | * @return TaxLine[]  | 
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| 460 | */  | 
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| 461 | public function getTaxLines()  | 
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| 465 | |||
| 466 | /**  | 
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| 467 | * @param TaxLine[] $taxLines  | 
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| 468 | *  | 
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| 469 | * @return LineItem  | 
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| 470 | */  | 
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| 471 | public function setTaxLines($taxLines)  | 
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| 477 | |||
| 478 | /**  | 
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| 479 | * @return float  | 
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| 480 | */  | 
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| 481 | public function getTotalDiscount()  | 
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| 485 | |||
| 486 | /**  | 
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| 487 | * @param float $totalDiscount  | 
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| 488 | *  | 
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| 489 | * @return LineItem  | 
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| 490 | */  | 
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| 491 | public function setTotalDiscount($totalDiscount)  | 
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| 497 | |||
| 498 | /**  | 
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| 499 | * @return DiscountAllocation[]  | 
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| 500 | */  | 
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| 501 | public function getDiscountAllocations()  | 
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| 505 | |||
| 506 | /**  | 
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| 507 | * @param DiscountAllocation[] $discountAllocations  | 
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| 508 | *  | 
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| 509 | * @return LineItem  | 
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| 510 | */  | 
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| 511 | public function setDiscountAllocations($discountAllocations)  | 
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| 517 | }  | 
            
This check looks for assignments to scalar types that may be of the wrong type.
To ensure the code behaves as expected, it may be a good idea to add an explicit type cast.