static <T> T deserialize(Reader s) {
        try {
            return MAPPER.readValue(s, new TypeReference<T>() {});
        } catch (IOException xany) {
            throw new RuntimeException(xany);
        }
    }
Performs an http client call.
@param jwt a JWT bearer token (can be null)
@param url the url to call
@param method the http method to use
@param json whether the call is application/json (true) or application/x-www-form-urlencoded (false)
@param arg the query argument
@return the (JSON) response
@throws IOException
standalone-metastore/metastore-rest-catalog/src/test/java/org/apache/iceberg/rest/HMSTestBase.java