It would be neccesary that contentTypeCheck be accepted also by contentTypeCheck.
For example line 309 of rest.cpp 
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else if ((ciP->httpHeaders.contentType != "application/xml") && (ciP->httpHeaders.contentType != "application/json"))
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should be replaced for example by:
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else if (((acceptTextXml == false) && (ciP->httpHeaders.contentType != "application/xml") && (ciP->httpHeaders.contentType != "application/json"))
            || ((acceptTextXml == true) && (ciP->httpHeaders.contentType != "application/xml") && (ciP->httpHeaders.contentType != "application/json") &
& (ciP->httpHeaders.contentType != "text/xml")))
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