java.net.ServerSocket. From documentation:

----- dolphin, b03 ----------
public ServerSocket(int port) throws IOException

Creates a server socket, bound to the specified port. A port of 0 creates a socket on any free port.
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In allmost all cases if user is not worry about port number he need this port number in future however. So he need to read all functions to search one that returns a port number. May be we should add link to getLocalPort() in description of this function. Smth like this:

A port number of 0 creates a socket on any free port. The port can be obtained later by getLocalPort().

Also applicable for ServerSocket(int port, int backlog)

Notes:
1. Incossistence in sentences:
ServerSocket(int port): A port of 0 creates a socket on any free port.
ServerSocket(int port, int backlog): A port number of 0 creates a socket on any free port.
It would be better to use one sentence to describe equal things.
2. TYPO:
If the value passed *if* equal or less than 0, then the default value will be assumed.