8308642: Unhelpful pattern switch error: illegal fall-through to a pattern

Reviewed-by: mcimadamore

Author: biboudis

src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties

@@ -574,10 +574,12 @@ compiler.err.constant.label.not.compatible=\
     constant label of type {0} is not compatible with switch selector type {1}
 
 compiler.err.flows.through.to.pattern=\
-    illegal fall-through to a pattern
+    illegal fall-through to a pattern\n\
+    (the previous case label is missing a break)
 
 compiler.err.flows.through.from.pattern=\
-    illegal fall-through from a pattern
+    illegal fall-through from a pattern\n\
+    (the current case label is missing a break)
 
 compiler.err.invalid.case.label.combination=\
     invalid case label combination