Method for retrieving the content of an item from MultiArchive.

The URN used for the method should be constructed in one of the following ways:
urn:multiarchive:content:A42:25-1
urn:multiarchive:content:A42:25-1#5

The first URN will retrieve the content of ItemMaster 25, compound sequence 1 and implicit the latest version.
The second URN will retrieve the content from the same document as the first URN, but here it is explicit specified that it shall retrieve the fifth (5.) version of the document.

public base64Binary RetrieveContent(
	Credentials credentials,
	string contentUrn
)

Public Function RetrieveContent ( 
	credentials As Credentials,
	contentUrn As String
) As base64Binary

public:
base64Binary^ RetrieveContent(
	Credentials^ credentials, 
	String^ contentUrn
)