Azure SAML2.0 not surport

[lzg553665176]

first，I need to say it vary perfect to me when I test my project on Azure saml. It all most run very well, but when azure callback /saml/acs，the issue was attempt!
expected element <Assertion> in name space urn:oasis:names:tc:SAML:2.0:assertion but have http://www.w3.org/2000/09/xmldsig#
the key code is here, it change xml and add xmlns namespane:
`func elementToBytes(el etree.Element) ([]byte, error) {
namespaces := map[string]string{}
for _, childEl := range el.FindElements("//") {
ns := childEl.NamespaceURI()
if ns != "" {
namespaces[childEl.Space] = ns
}
}

doc := etree.NewDocument()
doc.SetRoot(el.Copy())
for space, uri := range namespaces {
	doc.Root().CreateAttr("xmlns:"+space, uri)
}

return doc.WriteToBytes()

}`

azure org xml have 4 attr, but this function add 2，the xml become:
`

`

I don't know why need creat attr，some one can tell me if you kown.