setHeaderProperty
Sets HTTP header properties like cookies and charset.
General format
void setHeaderProperty( key, value )
Syntax rules
1. key is an alphanumeric data item that specifies the name of the property to set
2. value is an alphanumeric data item that specifies the value for the property
General rules
1. This method should be called before a request performed via one of the following methods: doGet, doPost, doPostEx or doPostMultipart.
2. key should be specified in lower case otherwise it’s not found. For example, in order to get the value of "Content-Type", look for "content-type".