Add missing file RecordPatternsPreview1ExhaustivenessOK1.java for JDK 21

This file was missing, which did not trigger an error in CI builds,
because AllTestsAspectJ1921 was not part of the AllTests19 suite before.
The latter will be fixed in the next commit.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

tests/features1921/java21/RecordPatternsPreview1ExhaustivenessOK1.java

@@ -0,0 +1,34 @@
+public class RecordPatternsPreview1ExhaustivenessOK1 {
+  static Pair<A> p1 = new Pair<>(new A(), new B());
+  static Pair<I> p2 = new Pair<>(new C(), new D());
+
+  public static void main(String[] args) {
+    exhaustiveSwitch();
+  }
+
+  static void exhaustiveSwitch() {
+    switch (p2) {
+      case Pair<I>(I i, C c) -> System.out.println("x");
+      case Pair<I>(I i, D d) -> System.out.println("y");
+      // Redundant default clause no longer necessary after fix of https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455.
+      // Old version with default clause see features1919/java19/RecordPatternsPreview1ExhaustivenessOK1.java.
+      // default -> System.out.println("z");
+    }
+
+    switch (p2) {
+      case Pair<I>(C c, I i) -> System.out.println("a");
+      case Pair<I>(D d, C c) -> System.out.println("b");
+      case Pair<I>(D d1, D d2) -> System.out.println("c");
+      // Redundant default clause no longer necessary after fix of https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455.
+      // Old version with default clause see features1919/java19/RecordPatternsPreview1ExhaustivenessOK1.java.
+      // default -> System.out.println("d");
+    }
+  }
+}
+
+class A { }
+class B extends A { }
+sealed interface I permits C, D { }
+final class C implements I { }
+final class D implements I { }
+record Pair<T>(T x, T y) { }