title: Get the metadata of an order item in woocommerce 3
body: <p>how to get metadata of a product woocommerce?
  I have  field custom en my products and I need to get this data.</p>
  
  <pre><code>{"ID":151,
   "ORDER_ID":251,
   "NAME":"car",
   "PRODUCT_ID":87,
   "VARIATION_ID":0,
   "QUANTITY":1,
   "TAX_CLASS":"",
   "SUBTOTAL":"3",
   "SUBTOTAL_TAX":"0",
   "TOTAL":"3",
   "TOTAL_TAX":"0",
   "TAXES":{"TOTAL":[],
            "SUBTOTAL":[]},
   "META_DATA":[{"ID":1433,
                 "KEY":"my_car",
                 "VALUE":"red"}]}
  </code></pre>
  
  <p>But the always result is the same, I can't access to field <code>meta_data</code>. The field <code>ID</code> and <code>name</code> I have access.</p>
  
  <p>I used <code>get_data()</code> and <code>get_item()</code>, but when I try access with <code>get_data()</code> to field  <code>meta_data</code> it give me this error:</p>
  
  <pre><code> UNCAUGHT ERROR: CANNOT USE OBJECT OF TYPE WC_DATETIME AS ARRAY IN  
  </code></pre>
  
  <p>And with <code>get_item()</code>, the value <code>meta_data</code> is null because is protected.</p>
  
  <p>How can i get these values?</p>