code: public StringBuilder appendTypeArguments(JvmParameterizedTypeReference typeRef, StringBuilder result) {
  		List<JvmTypeReference> typeArguments = typeRef.getArguments();
  		if (typeArguments.isEmpty()) {
  			throw new IllegalArgumentException("typeRef is not parameterized");
  		}
  		result.append("<");
  		for(int i = 0, size = typeArguments.size(); i < size; i++) {
  			if (i != 0) {
  				result.append(", ");
  			}
  			result = visit(typeArguments.get(i), result);
  			if (result == null)
  				return null;
  		}
  		result.append(">");
  		return result;
  	}
docs: /* @Nullable