Account for new possible child index gap

Author: smowton

java/ql/consistency-queries/children.ql

@@ -49,6 +49,8 @@ predicate gapInChildren(Element e, int i) {
   not e instanceof Annotation and
   // Pattern case statements legitimately have a TypeAccess (-2) and a pattern (0) but not a rule (-1)
   not (i = -1 and e instanceof PatternCase and not e.(PatternCase).isRule()) and
+  // Pattern case statements can have a gap at -3 when they have more than one pattern but no guard.
+  not (i = -3 and count(e.(PatternCase).getAPattern()) > 1 and not exists(e.(PatternCase).getGuard())) and
   // Instanceof with a record pattern is not expected to have a type access in position 1
   not (i = 1 and e.(InstanceOfExpr).getPattern() instanceof RecordPatternExpr) and
   // RecordPatternExpr extracts type-accesses only for its LocalVariableDeclExpr children