import java.util.HashMap;

import java.util.Map;

public class QueryStringStripper {

public static Map<String, String> stripMetadata(String queryString) {

Map<String, String> params = new HashMap<>();

if (queryString == null || queryString.isEmpty()) {

return params;

}

String[] pairs = queryString.split("&");

for (String pair : pairs) {

if (pair != null && !pair.isEmpty()) {

String[] parts = pair.split("=");

if (parts.length == 2) {

String key = parts[0];

String value = parts[1];

//Remove metadata prefix (e.g., # or %20)

if (key.startsWith("#")) {

key = key.substring(1);

}

if (key.startsWith("%")) {

key = decodeURIComponent(key);

}

params.put(key, value);

}

}

}

return params;

}

private static String decodeURIComponent(String str) {

//Simple implementation for demonstration. More robust solutions exist.

return str;

}

public static void main(String[] args) {

String queryString = "param1=value1&param2=%20value2&param3=#value3";

Map<String, String> params = stripMetadata(queryString);

System.out.println(params); //Expected output: {param1=value1, param2= value2, param3=value3}

queryString = "param1=value1";

params = stripMetadata(queryString);

System.out.println(params); //Expected output: {param1=value1}

queryString = null;

params = stripMetadata(queryString);

System.out.println(params); //Expected output: {}

}

}