$ mvn compile   # legacy sources, only the Boot version changed to 4.1.1 (Batch 6.0.5)
compile error lines reported: 56

packages that no longer exist:
package org.springframework.batch.core.explore does not exist
package org.springframework.batch.item does not exist
package org.springframework.batch.item.support does not exist

classes that moved:
ChunkListener ItemReader ItemWriter Job JobExecution JobExplorer JobParameters JobParametersBuilder ListItemReader Step