title: Service operation GetCategories is unknown
body: <p>Ebay supports a few ways of doing an API call including Name-Value pairs and XML. Almost all examples are in XML. 
  Please help me translate the following XML code into JSONP URL  </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;GetCategoriesRequest xmlns="urn:ebay:apis:eBLBaseComponents"&gt;
      &lt;RequesterCredentials&gt;
          &lt;eBayAuthToken&gt;ABC...123&lt;/eBayAuthToken&gt;
      &lt;/RequesterCredentials&gt;
      &lt;CategorySiteID&gt;0&lt;/CategorySiteID&gt;
      &lt;DetailLevel&gt;ReturnAll&lt;/DetailLevel&gt;
  &lt;/GetCategoriesRequest&gt;
  </code></pre>
  
  <p>I came up with this URL  </p>
  
  <pre><code>http://svcs.ebay.com/services/search/FindingService/v1
  ?SECURITY-APPNAME=DmitryKh-8c0f-4272-80d0-a0df7dca76f8
  &amp;OPERATION-NAME=GetCategories
  &amp;SERVICE-VERSION=1.0.0
  &amp;RESPONSE-DATA-FORMAT=JSON
  &amp;callback=_cb_findCategories
  &amp;REST-PAYLOAD
  &amp;CategorySiteID=0
  &amp;DetailLevel=ReturnAll
  </code></pre>
  
  <p>But it gives me error message "Service operation GetCategories is unknown"  </p>
  
  <p><code>/**/_cb_findCategories({"errorMessage":[{"error":[{"errorId":["2000"],"domain":["CoreRuntime"],"severity":["Error"],"category":["Request"],"message":["Service operation GetCategories is unknown"],"subdomain":["Inbound_Meta_Data"],"exceptionId":["com.ebay.soaframework.common.exceptions.ServiceException"],"parameter":[{"@name":"Param1","__value__":"GetCategories"}]}]}]})</code></p>