Specifies a TStream descendant class instance that contains the binary content to include as the content part. This property and the Content property are mutually-exclusive. If both properties are assigned a value, then the ContentStream property will take precedence.
If this property is assigned a value and the Content-Type header is not specified using the Headers property, it will be automatically set to "application/octet-stream" when the server request is executed.
This is just a reference to the TStream descendant class instance, so please make sure that you do not free this class instance before the TServerRequest Execute method is called.