GH 4755: Fix wrong behavior of JobRepository with empty identifying job parameters

Signed-off-by: Seungyong Hong <[email protected]>

Author: isanghaessi

spring-batch-core/src/main/java/org/springframework/batch/core/launch/support/TaskExecutorJobLauncher.java

@@ -63,6 +63,7 @@
  * @author Will Schipp
  * @author Michael Minella
  * @author Mahmoud Ben Hassine
+ * @author Seungyong Hong
  * @since 1.0
  * @see JobRepository
  * @see TaskExecutor
@@ -144,8 +145,7 @@ private JobExecution createJobExecution(Job job, JobParameters jobParameters)
 					JobParameters allJobParameters = execution.getJobParameters();
 					JobParameters identifyingJobParameters = new JobParameters(
 							allJobParameters.getIdentifyingParameters());
-					if (!identifyingJobParameters.isEmpty()
-							&& (status == BatchStatus.COMPLETED || status == BatchStatus.ABANDONED)) {
+					if (status == BatchStatus.COMPLETED || status == BatchStatus.ABANDONED) {
 						throw new JobInstanceAlreadyCompleteException(
 								"A job instance already exists and is complete for identifying parameters="
 										+ identifyingJobParameters + ".  If you want to run this job again, "