SecurityManager is deprecated for removal

[cushon]

SecurityManager is deprecated for removal, see also https://openjdk.org/jeps/486

It is used in procyon in CallerResolver for SecurityManager#getClassContext:

https://github.com/mstrobel/procyon/blob/88a95fa93c58322393174f84543edc7a0a2ca44d/Procyon.Core/src/main/java/com/strobel/compilerservices/CallerResolver.java#L19C43-L19C58

That use-case could be migrated to java.lang.StackWalker, with something like:

public final class CallerResolver {
    private static final StackWalker STACK_WALKER =
            StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE);
    private static final int CALL_CONTEXT_OFFSET = 1; // may need to change if this class is redesigned

    /**
     * Indexes into the current method call context with a given offset.
     */
    public static Class getCallerClass(final int callerOffset) {
        return STACK_WALKER
                .walk(
                        s -> s.skip(CALL_CONTEXT_OFFSET + callerOffset)
                                .map(StackWalker.StackFrame::getDeclaringClass)
                                .findFirst())
                .get();
    }
}

The StackWalker API was added in Java 9, and I think procyon is compatible with JDK 7. To migrate while continuing to support JDK 7 it would be possible to use reflection to access StackWalker, or a multi-release jar.