remove utility classes (#1733)

* remove utility classes

* remove httpclient, extend http

* move code to core-java

core-java/src/main/java/com/baeldung/http/ParameterStringBuilder.java

@@ -0,0 +1,21 @@
+package com.baeldung.http;
+
+import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
+import java.util.Map;
+
+public class ParameterStringBuilder {
+    public static String getParamsString(Map<String, String> params) throws UnsupportedEncodingException {
+        StringBuilder result = new StringBuilder();
+
+        for (Map.Entry<String, String> entry : params.entrySet()) {
+            result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
+            result.append("=");
+            result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
+            result.append("&");
+        }
+
+        String resultString = result.toString();
+        return resultString.length() > 0 ? resultString.substring(0, resultString.length() - 1) : resultString;
+    }
+}