Only define netbeans_debug if not already specified

Author: jtulach

BUILD.MD

@@ -148,6 +148,25 @@ are being passed to the `code` by default:
 The script also instructs the system to print messages (stderr, out) to the console
 by adding `-J-Dnetbeans.logger.console=true` to the npm commandline.
 This has the same effect as `netbeans.verbose = true` settings in the vscode.
+Following summary is printed when using `npm run nbcode`:
+
+```bash
+Launching `code` with following arguments:
+  --extensionDevelopmentPath=/netbeans-vscode/vscode
+  --user-data-dir=/netbeans-vscode/vscode/out/userdir
+  --extensions-dir=/netbeans-vscode/vscode/out/extdir
+and following additional environment variables:
+  netbeans_debug=-J-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000
+```
+
+With such a summary of arguments passed `code` to
+the code as well as environment variables additionally provided to the process one can
+fully understand what the script is doing. The `netbeans_debug` variable is only added
+if not already specified. As such one can fully control the debugging arguments by
+defining the variable before executing the `npm` script:
+```bash
+netbeans_debug=-J-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=7777 npm run nbcode
+```
 
 <!--
 ### NBLS userdir locations

vscode/src/nbcode.ts

@@ -119,16 +119,24 @@ if (typeof process === 'object' && typeof process.argv0 ==='string' && process.a
         "--user-data-dir=" + datadir,
         "--extensions-dir=" + extdir
     ].concat(args);
-    let extraEnv: NodeJS.ProcessEnv = {
+    let extraEnv: NodeJS.ProcessEnv = env.netbeans_debug ? {
+        // no override of netbeans_debug
+    } : {
         netbeans_debug : '-J-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000'
     }
     console.log('Launching `code` with following arguments:');
     for (var arg of codeArgs) {
         console.log(`  ${arg}`);
     }
-    console.log('and following additional environment variables:');
-    for (var name in extraEnv) {
-        console.log(`  ${name}=${extraEnv[name]}`);
+    {
+        let first = true;
+        for (var name in extraEnv) {
+            if (first) {
+                console.log('and following additional environment variables:');
+                first = false;
+            }
+            console.log(`  ${name}=${extraEnv[name]}`);
+        }
     }
 
     let codeProc: ChildProcessByStdio<any, Readable, Readable> = spawn("code", codeArgs, {