Check for a behavior change on the DatagramPacket.getPort() method

This rule flags Java code with calls to the java.net.DatagramPacket.getPort() method. In Java SE 15, the default return value when the port is not set was changed from -1 to 0. You will need to evaluate whether your application is affected by the behavior change and make any necessary updates.

For more information on these changes, see Other notes in Java SE 15.