Add test cases to cover key generation for empty identifying job parameters set

Related to #4755

Signed-off-by: Fabrice Bibonne <fabrice.bibonne@gmail.com>

Author: fmbenhassine

spring-batch-core/src/test/java/org/springframework/batch/core/DefaultJobKeyGeneratorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2022 the original author or authors.
+ * Copyright 2013-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -65,4 +65,22 @@ void testCreateJobKeyOrdering() {
 		assertEquals(key1, key2);
 	}
 
+	@Test
+	public void testCreateJobKeyForEmptyParameters() {
+		JobParameters jobParameters1 = new JobParameters();
+		JobParameters jobParameters2 = new JobParameters();
+		String key1 = jobKeyGenerator.generateKey(jobParameters1);
+		String key2 = jobKeyGenerator.generateKey(jobParameters2);
+		assertEquals(key1, key2);
+	}
+
+	@Test
+	public void testCreateJobKeyForEmptyParametersAndNonIdentifying() {
+		JobParameters jobParameters1 = new JobParameters();
+		JobParameters jobParameters2 = new JobParametersBuilder().addString("name", "foo", false).toJobParameters();
+		String key1 = jobKeyGenerator.generateKey(jobParameters1);
+		String key2 = jobKeyGenerator.generateKey(jobParameters2);
+		assertEquals(key1, key2);
+	}
+
 }