code: def _contentful_user_agent(self):
          
          header = {}
          from . import __version__
          header['sdk'] = {
              'name': 'contentful-management.py',
              'version': __version__
          }
          header['app'] = {
              'name': self.application_name,
              'version': self.application_version
          }
          header['integration'] = {
              'name': self.integration_name,
              'version': self.integration_version
          }
          header['platform'] = {
              'name': 'python',
              'version': platform.python_version()
          }
  
          os_name = platform.system()
          if os_name == 'Darwin':
              os_name = 'macOS'
          elif not os_name or os_name == 'Java':
              os_name = None
          elif os_name and os_name not in ['macOS', 'Windows']:
              os_name = 'Linux'
          header['os'] = {
              'name': os_name,
              'version': platform.release()
          }
  
          def format_header(key, values):
              header = "{0} {1}".format(key, values['name'])
              if values['version'] is not None:
                  header = "{0}/{1}".format(header, values['version'])
              return "{0};".format(header)
  
          result = []
          for k, values in header.items():
              if not values['name']:
                  continue
              result.append(format_header(k, values))
  
          return ' '.join(result)
docs: Sets the X-Contentful-User-Agent header.