In Monitoring applet, parameter of an executed request is left to blank, should have all events with assigned value on Attribute1 is not working

When the parameter of an executed request is left to blank, it is internally replaced with the character '%'.
When filling with nothing and click on OK, you should have all events with assigned value on Attribute1.But get a message "Value missing" if we do not select any value and press OK.

Problem is found to be fixed with adding of the line

set SENTINEL_DEFINE=%SENTINEL_DEFINE% -DEMPTYVALUEFORTRKPARAMETER=true

in trkserver.bat file.