https://github.com/groovy/groovy-core/blob/master/src/main/org/codehaus/groovy/runtime/DefaultGroovyMethods.java
https://github.com/groovy/groovy-core/blob/master/src/main/org/codehaus/groovy/runtime/ResourceGroovyMethods.java
    https://github.com/groovy/groovy-core/blob/master/src/main/org/codehaus/groovy/runtime/ResourceGroovyMethods.java#L667
    public static String getText(URL url, Map parameters, String charset) throws IOException {
        BufferedReader reader = newReader(url, parameters, charset);
        return IOGroovyMethods.getText(reader);
    }
    https://github.com/groovy/groovy-core/blob/master/src/main/org/codehaus/groovy/runtime/ResourceGroovyMethods.java#L2134
    public static BufferedReader newReader(URL url, Map parameters, String charset) throws MalformedURLException, IOException {
        return new BufferedReader(new InputStreamReader(configuredInputStream(parameters, url), charset));
    }
    https://github.com/groovy/groovy-core/blob/master/src/main/org/codehaus/groovy/runtime/ResourceGroovyMethods.java#L2010
    private static InputStream configuredInputStream(Map parameters, URL url) throws IOException {
        final URLConnection connection = url.openConnection();
        if (parameters != null) {
            ...
        }
    }
https://github.com/groovy/groovy-core/blob/master/src/main/org/codehaus/groovy/runtime/IOGroovyMethods.java


https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/net/URLConnection.html
https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/net/HttpURLConnection.html
    https://stackoverflow.com/questions/12732422/adding-header-for-httpurlconnection
    .setRequestProperty(<name>, <value>)
    https://self-learning-java-tutorial.blogspot.com/2017/09/adding-headers-using-httpurlconnection.html