protected String toStringExpression(JType type, String expr) {
    if (type.isPrimitive() != null) {
      return "\"\"+" + expr;
    }
    if (STRING_TYPE == type) {
      return expr;
    }
    if (type.isClass() != null && isOverlayArrayType(type.isClass())) {
      return "(new " + JSON_ARRAY_CLASS + "(" + expr + ")).toString()";
    }
    if (type.isClass() != null && OVERLAY_VALUE_TYPE.isAssignableFrom(type.isClass())) {
      return "(new " + JSON_OBJECT_CLASS + "(" + expr + ")).toString()";
    }

    return String.format("(%s != null ? %s.toString() : null)", expr, expr);
  }
  protected String toFormStringExpression(JParameter argument, Style classStyle)
      throws UnableToCompleteException {
    JType type = argument.getType();
    String expr = argument.getName();

    if (type.isPrimitive() != null) {
      return "\"\"+" + expr;
    }
    if (STRING_TYPE == type) {
      return expr;
    }
    if (type.isClass() != null && isOverlayArrayType(type.isClass())) {
      return "(new " + JSON_ARRAY_CLASS + "(" + expr + ")).toString()";
    }
    if (type.isClass() != null && OVERLAY_VALUE_TYPE.isAssignableFrom(type.isClass())) {
      return "(new " + JSON_OBJECT_CLASS + "(" + expr + ")).toString()";
    }
    if (type.getQualifiedBinaryName().startsWith("java.lang.")) {
      return String.format("(%s != null ? %s.toString() : null)", expr, expr);
    }

    Json jsonAnnotation = argument.getAnnotation(Json.class);
    final Style style = jsonAnnotation != null ? jsonAnnotation.style() : classStyle;

    return locator.encodeExpression(type, expr, style) + ".toString()";
  }