Socket.getOption(StandardSocketOptions.SO_LINGER) does not return the
expected type, when invoked on a socket that has not had its setOption
equivalent invoke to set the option. The expected returned type is
Integer, but the actual type is Boolean.

For example:

  $ jdk-12.jdk/Contents/Home/bin/jshell
  | Welcome to JShell -- Version 12
  | For an introduction type: /help intro
  
  jshell> var s = new Socket()
  s ==> Socket[unconnected]

  jshell> s.getOption(StandardSocketOptions.SO_LINGER)
  | Exception java.lang.ClassCastException: class java.lang.Boolean cannot be cast to class java.lang.Integer (java.lang.Boolean and java.lang.Integer are in module java.base of loader 'bootstrap')
  | at (#2:1)

---

There are also issues when negative values are set. For example:

  jshell> var s = new Socket()
  s ==> Socket[unconnected]

  jshell> s.setOption(StandardSocketOptions.SO_LINGER, -1)
  $4 ==> Socket[unconnected]

  jshell> s.getOption(StandardSocketOptions.SO_LINGER)
  $5 ==> 65535