OutputModelFactory + SourceGenTriggers

- The output model factory has to allow null results on almost all methods.
- Added SourceGenTriggers tree walker (not cleaned up yet).

package.json

@@ -18,7 +18,7 @@
         "antlr4ng": "3.0.7",
         "commander": "12.1.0",
         "fast-printf": "1.6.9",
-        "stringtemplate4ts": "1.0.1",
+        "stringtemplate4ts": "1.0.2",
         "unicode-properties": "1.4.1"
     },
     "devDependencies": {

src/antlr3/tree/TreeRuleReturnScope.ts

@@ -15,6 +15,7 @@ import type { Tree } from "./Tree.js";
  * have to be {@link Object}.
  */
 export class TreeRuleReturnScope {
+
     /** First node or root node of tree matched for this rule. */
     public start: Tree | null = null;
     public stop: Tree | null = null;

src/tree-walkers/BlockSetTransformer.ts

@@ -1,3 +1,5 @@
+/* java2ts: keep */
+
 // $ANTLR 3.5.3 org/antlr/v4/parse/BlockSetTransformer.g
 
 import {

src/tree-walkers/GrammarTreeVisitor.ts

@@ -1,3 +1,5 @@
+/* java2ts: keep */
+
 /*
  * Copyright (c) The ANTLR Project. All rights reserved.
  * Use of this file is governed by the BSD 3-clause license that
@@ -5582,7 +5584,6 @@ export class GrammarTreeVisitor extends TreeParser {
     protected exitElementOption(tree: GrammarAST): void { }
 }
 
-
 export namespace GrammarTreeVisitor {
     export type grammarSpec_return = InstanceType<typeof GrammarTreeVisitor.grammarSpec_return>;
     export type prequelConstructs_return = InstanceType<typeof GrammarTreeVisitor.prequelConstructs_return>;

src/tree-walkers/LeftRecursiveRuleWalker.ts

@@ -1,3 +1,5 @@
+/* java2ts: keep */
+
 // $ANTLR 3.5.3 org/antlr/v4/parse/LeftRecursiveRuleWalker.g