[1] 2.2.5.8 X-HTTP-Method ( ( 版)) <http://msdn.microsoft.com/en-us/library/dd541471.aspx>
[2] Complete basic operations using SharePoint 2013 REST endpoints ( 版) <https://msdn.microsoft.com/en-us/library/office/jj164022.aspx>
X-HTTP-Method header
POST requests for DELETE, MERGE, or PUT operations
Used to specify that the request performs an update or delete operation. Example: "X-HTTP-Method":"PUT"