Surface the real reason a job execution cannot be restarted

SimpleJobOperator.restart(JobExecution) caught every exception thrown by run(...) and rewrapped it into a JobRestartException with a hardcoded "job execution already running" message. This masked the actual reason reported by the launcher — most notably "Cannot restart job from UNKNOWN status" — sending users down the wrong debugging path.

Catch only JobExecutionAlreadyRunningException for the "already running" message, wrap JobInstanceAlreadyCompleteException and InvalidJobParametersException with their own messages, and let JobRestartException propagate unchanged so its specific message survives.

Resolves #5439

Author: kyungrae

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

@@ -245,10 +245,13 @@ public JobExecution restart(JobExecution jobExecution) throws JobRestartExceptio
 		try {
 			return run(job, parameters);
 		}
-		catch (Exception e) {
+		catch (JobExecutionAlreadyRunningException e) {
 			throw new JobRestartException(
 					String.format(ILLEGAL_STATE_MSG, "job execution already running", jobName, parameters), e);
 		}
+		catch (JobInstanceAlreadyCompleteException | InvalidJobParametersException e) {
+			throw new JobRestartException(e.getMessage(), e);
+		}
 
 	}