When the program starts, it should open a server socket to listen for connections on port 8081. When a client connection is received, the program should make new thread to handle the connection. The worker thread should read a single line of text from the connection (up to the newline character), write the line back to the client connection, and close the connection. The program should accept new connections until it is forcibly shut down. The program must be multi-threaded and be capable of responding to multiple requests at once.

Helpful Hints:

• Use the java.net.ServerSocket class to open a port and listen for new connections (see chapter 3 of the textbook for more information).
• Use the java.net.ServerSocket.accept() method to accept a new client connection.
• You can read from and write to the data streams in java.net.ServerSocket.getOutputStream() and java.net.ServerSocket.getInputStream() just as if they were files or standard input/output.