.toUpperCase() doesn't work in the simple expression below.

<simple>'{{mainframe.filename}}.$simple{$simple{file:onlyname.noext}.toUpperCase()}.$simple{date:now:'D'yyMMdd}.$simple{date:now:'T'HHmmsss}'</simple>
I need to send a upper cased file name to mainframe and the expression above
throws the following error.
Is there a work around for this issue ?

org.apache.camel.language.simple.types.SimpleIllegalSyntaxException: Unknown
function: mediacashpaid.toUpperCase() at location 26
'DDSTEST.SAP.ZBTO.SAPFILE.$simple{$simple{file:onlyname.noext}.toUpperCase()}.$simple{date:now:'D'yyMMdd}.$simple{date:now:'T'HHmmsss}'