the request body doesn't directly support it, but @████████ can confirm this.

What I'm saying (and what is missing from your example) is where you are actually attaching the file binary to the request. That part of your code is where the mimetype should come from.

Where are you making this request? Do you own that codebase? Is it Laserfiche to Laserfiche?

I am making this request from my python app to Laserfiche cloud. The python app is downloading files from an external web app then importing them into LF. 

Here's the relevant portion of my code. 
 

            # Prepare import request - use the new folder's ID
            import_url = f"{self.base_url}/Repositories/{self.config.repository_id}/Entries/{folder_entry_id}/Folder/Import"
            
            # Determine content type
            # Check if content is PDF by magic number
            is_pdf = isinstance(file_content, bytes) and file_content.startswith(b'%PDF')
            
            # Set appropriate content type - probably a pdf first, then word
            if is_pdf:
                content_type = 'application/pdf'
                # Add .pdf extension if it's missing
                if not file_name.lower().endswith('.pdf'):
                    file_name = f"{file_name}.pdf"
                print(f"Using PDF content type for {file_name}")
            else:
                # Use magic to detect content type
                content_type = magic.from_buffer(file_content, mime=True)
                if content_type == "application/msword":
                    file_name = f"{file_name}.doc"
                print(f"Using detected content type: {content_type} for {file_name}")

            # Prepare request data
            # Get template name from metadata or default to Building
            template_name = metadata.get("templateName") if metadata else "Building"

            # Base request data structure
            base_request = {
                "name": file_name,
                "autoRename": True,
                "pdfOptions": {
                    "generateText": True,
                    "generatePages": True,
                    "generatePagesImageType": "StandardColor", 
                    "keepPdfAfterImport": False
                }
            }

            # Prepare multipart form data
            files = {
                'file': (file_name, file_content, content_type)
            }
            
            # Send import request
            print(f"Sending import request to: {import_url}")
            response = requests.post(
                import_url,
                headers=self._get_headers(),
                files=files,
                data={
                    'request': json.dumps(request_data)
                }
            )

Based on what you are saying passing in the contentType with 'files' and packaging it with the POST should suffice. 

I am seeing an error in my code also...I don't believe I am explicitly defining contentType.