I set the configuration file (debug.json) in the plugin settings in atom UI.
However, on looking at the go-debug plugin code (dlv-connection.js), I observe that the configuration file is not being read at all. I might be wrong. please check. I am on v1.6.2 plugin.
The code added below worked !
config = Object.assign( config, JSON.parse( fs.readFileSync( variables.fileDirname + '/debug.json' ) ).configurations[0] )