@Override
	public void otherAlt(AltAST originalAltTree, int alt) {
		AltAST altTree = (AltAST)originalAltTree.dupTree();
		stripAltLabel(altTree);
		String altText = text(altTree);
		String altLabel = altTree.altLabel!=null ? altTree.altLabel.getText() : null;
		LeftRecursiveRuleAltInfo a =
			new LeftRecursiveRuleAltInfo(alt, altText, null, altLabel, false, originalAltTree);
		// We keep other alts with prefix alts since they are all added to the start of the generated rule, and
		// we want to retain any prior ordering between them
		prefixAndOtherAlts.add(a);
//		System.out.println("otherAlt " + alt + ": " + altText);
	}
Tokens from which rule AST comes from
tool/src/org/antlr/v4/analysis/LeftRecursiveRuleAnalyzer.java