docs(dotnet): ability to generate generics and null on path args (#5824)

Author: avodovnik

utils/doclint/generateDotnetApi.js

@@ -469,8 +469,8 @@ function renderMethod(member, parent, output, name) {
 
     if (arg.type.expression === '[string]|[path]') {
       let argName = translateMemberName('argument', arg.name, null);
-      pushArg("string", argName, arg);
-      pushArg("string", `${argName}Path`, arg);
+      pushArg("string", `${argName} = null`, arg);
+      pushArg("string", `${argName}Path = null`, arg);
       if (arg.spec) {
         addParamsDoc(argName, XmlDoc.renderTextOnly(arg.spec, maxDocumentationColumnWidth));
         addParamsDoc(`${argName}Path`, [`Instead of specifying <paramref name="${argName}"/>, gives the file name to load from.`]);
@@ -691,6 +691,13 @@ function translateType(type, parent, generateNameCallback = t => t.name) {
     }
   }
 
+  if (type.templates) {
+    // this should mean we have a generic type and we can translate that
+    /** @type {string[]} */
+    var types = type.templates.map(template => translateType(template, parent));
+    return `${type.name}<${types.join(', ')}>`
+  }
+
   // there's a chance this is a name we've already seen before, so check
   // this is also where we map known types, like boolean -> bool, etc.
   let name = classNameMap.get(type.name) || type.name;