org.apache.http.client.utils.URLEncodedUtils.parse() should return a new ArrayList when there are no query parameters

org.apache.http.client.utils.URLEncodedUtils.parse(URI, Charset) should return a new ArrayList when there are no query parameters.

Currently, org.apache.http.client.utils.URLEncodedUtils.parse(URI, Charset) returns an immutable list through Collections.emptyList() if there are no params> But if there are parameters, the method returns a mutable list.

This makes it impossible to write the same code to handle both cases.

This change will cause the method to return a new ArrayList if there are no parameters.

The methods that are directly affected are:

• org.apache.http.client.utils.URLEncodedUtils.parse(URI, Charset)
• org.apache.http.client.utils.URLEncodedUtils.parse(HttpEntity)
• org.apache.http.client.utils.URLEncodedUtils.parse(String, Charset)
• org.apache.http.client.utils.URLEncodedUtils.parse(String, Charset, char...)