It's Boolean Union! ;)

so Make a shortcut with BooleanUnion in the second column
or Press Tab and write BooleanUnion
with any capitals or not but without space! (so BoolEanUNIOn, BOOleanUnion, booleanunion ...etc are valid)

If you want a comment in your ShortCut
script: /* Boolean Union for simulate Trim lines & Join */ script:moi.command.execCommand( 'BooleanUnion' );

(sorry i have not seen the Michael post! But now you have a little more info! :)