Finds an XML document that has been loaded by the specified URI.
If the parameter key is specified, the found document must also be associated
with that key. See description of loadXMLDocument() function for more details.
Parameter:
xmlURI
key
#DOCUMENT type that represents the found XML document.
The function returns null when:
key is specified and none of the XML documents
loaded by that URI is associated with the specified key.
#DOCUMENT, #DOCUMENT@xmlURI, #DOCUMENTS;loadXMLDocument(), getXMLDocument()