New language features supported (all described by https://openjdk.org/jeps/456):

• Anonymous variables (e.g. TypeName _), which can occur in declarations and binding patterns.
• Anonymous lambda parameters
• Anonymous patterns (spelled simply _), which can occur in record-pattern context (e.g. MyRecord(int x, _))
• Multiple patterns in one switch case statement, so long as no pattern declares any binding variables (case A _, B _ when sharedGuard)
• Fall-through to and from pattern-case statements that don't declare any binding variables (case A _: case "Constant": case MyRecord(_):)

Anonymous variables, lambda parameters and patterns only require pretty-printing and some formatting; they can naturally never take part in dataflow and their names are irrelevant in QL.

Most of the work goes into pattern cases gaining multiple possible patterns (which means the pattern will be entered if one or other pattern matches), and into implementing fall-through. This in particular has consequences for control flow, where pattern-case statements (which normally represent carrying out the type test(s)) need to be circumvented by fall-through flow (e.g. in the context case A _: f(); case B _: g(); break;, the successor of f() is g(), not a type test for B).