[Proposed]
Set maxOccurs="1"
Explicitly use "a single ReturnType element" in the prose text.
Accepted: https://www.oasis-open.org/apps/org/workgroup/odata/download.php/47230/latest/odata_meeting-12_on-20121018-minutes.html
https://www.oasis-open.org/apps/org/workgroup/odata/download.php/47437/odata-core-v1.0-wd01-part3-csdl-2012-11-12-RH.doc https://tools.oasis-open.org/version-control/browse/wsvn/odata/trunk/spec/schemas/csdl.xsd?rev=97
Accepted: https://www.oasis-open.org/apps/org/workgroup/odata/download.php/47595/latest/odata-meeting-16_on-20121129-minutes.html
Currently the XSD specifies maxOccurs="unbounded" for the ReturnType child element of a FunctionImport.
The prose only talks of "a ReturnType element".