additionalProperties: function (report, schema) {
        // http://json-schema.org/latest/json-schema-validation.html#rfc.section.5.4.4.1
        var type = Utils.whatIs(schema.additionalProperties);
        if (type !== "boolean" && type !== "object") {
            report.addError("KEYWORD_TYPE_EXPECTED", ["additionalProperties", ["boolean", "object"]]);