code: public String getMultipartClass()
      {
          if ( _forceMultipartDisabled ) return null;
          if ( _overrideMultipartClass != null ) return _overrideMultipartClass;
  
          MultipartHandler mpHandler = InternalUtils.getMultipartHandlerType();
          
          if ( mpHandler != null )
          {
              switch ( mpHandler.getValue() )
              {
                  case MultipartHandler.INT_DISABLED: return null;
                  case MultipartHandler.INT_MEMORY: return COMMONS_MULTIPART_HANDLER_CLASS;
                  case MultipartHandler.INT_DISK: return COMMONS_MULTIPART_HANDLER_CLASS;
                  default: assert false : "unknown value for multipart handler: " + mpHandler.toString();
              }
          }
          
          return null;
      }
docs: This gets the multipart class.  If it was explicitly set on the associated <controller> element, just use that;
  otherwise, get the value from WEB-INF/beehive-netui-config.xml.