=== javac FinalOverride.java ===
FinalOverride.java:6: error: locked() in Derived cannot override locked() in Base
    String locked() { return "Derived.locked"; }
           ^
  overridden method is final
1 error

=== javac CheckedNotHandled.java ===
CheckedNotHandled.java:6: error: unreported exception IOException; must be caught or declared to be thrown
        String s = Files.readString(Path.of("missing.txt"));
                                   ^
1 error

=== javac LossyCast.java ===
LossyCast.java:3: error: incompatible types: possible lossy conversion from double to int
        int x = 3.5;
                ^
LossyCast.java:4: error: incompatible types: possible lossy conversion from int to byte
        byte b = 200;
                 ^
2 errors

=== javac MissingReturnAndUnreachable.java ===
MissingReturnAndUnreachable.java:4: error: missing return statement
    }
    ^
1 error

=== javac --release 21 PreSuper.java ===
PreSuper.java:8: error: flexible constructors is not supported in -source 21
        super();
             ^
  (use -source 25 or higher to enable flexible constructors)
1 error

=== javac --release 25 PreSuper.java ===
compiled without errors