The equals and hashCode methods of java.net.URL may trigger a name service lookup (typically DNS) to resolve
the hostname or IP address. Depending on the configuration, and network status, this lookup can be time-consuming.
On the other hand, the URI class does not perform such lookups and is a better choice unless you specifically require the
functionality provided by URL.
In general, it is better to use the URI class until access to the resource is actually needed, at which point you can convert the
URI to a URL using URI.toURL().
This rule checks for uses of URL 's in Map and Set , and for explicit calls to the equals and
hashCode methods. It suggests reconsidering the use of URL in such scenarios to avoid potential performance issues related
to name service lookups.
