Improve complexity class of getASuccessorSwitchCase

java/ql/lib/semmle/code/java/Statement.qll

@@ -464,6 +464,14 @@ class SwitchCase extends Stmt, @case {
     this = any(SwitchStmt ss).getCase(result) or this = any(SwitchExpr se).getCase(result)
   }
 
+  /**
+   * Holds if this is the `n`th case of switch block `parent`.
+   */
+  pragma[nomagic]
+  predicate isNthCaseOf(StmtParent parent, int n) {
+    this.getCaseIndex() = n and this.getParent() = parent
+  }
+
   /**
    * Holds if this `case` is a switch labeled rule of the form `... -> ...`.
    */