[jdk19] Add support for new guard pattern

test/pretty/resource/before/Switch19.java

@@ -0,0 +1,33 @@
+// version 19:
+public class Switch19 {
+	String switchPatternMatching(Object o) {
+		return switch (o) {
+			case Integer i	-> String.format("int %d", i);
+			case Long l		-> String.format("long %d", l);
+			case Double d	-> String.format("double %f", d);
+			case String s	-> String.format("String %s", s);
+			default			-> o.toString();
+		};
+	}
+
+	String switchNull(Object o) {
+		return switch (o) {
+			case null, default	-> "?";
+		};
+	}
+
+	String switchGuardPattern(Object o) {
+		return switch (o) {
+			case String s when s.length() > 1	-> s;
+			case String s 						-> s;
+			default								-> o.toString();
+		};
+	}
+
+	String switchParenthesizedPattern(Object o) {
+		return switch (o) {
+			case (String s)	-> s;
+			default			-> o.toString();
+		};
+	}
+}