toString method
A string representation of this object.
Some classes have a default textual representation,
often paired with a static parse function (like int.parse).
These classes will provide the textual representation as
their string representation.
Other classes have no meaningful textual representation
that a program will care about.
Such classes will typically override toString to provide
useful information when inspecting the object,
mainly for debugging or logging.
Implementation
@override
String toString() {
final pairs = map.entries.map((e) => '${Uri.encodeComponent(e.key)}=${Uri.encodeComponent(e.value)}');
return pairs.join('&');
}