Bug description
If an application is using the JsonLineMapper but is stuck with using Jackson 2.x, it will break.

Environment
Java 25, Spring Batch 6, H2 database

Steps to reproduce

• Create a Java application that has spring-batch-infrastructure as a dependency, typically a spring batch application
• Add a jackson-databind v2 dependency
• Have a usage of the JsonLineMapper in the application
• Execute the application

Exception in thread "main" java.lang.NoClassDefFoundError: tools/jackson/databind/json/JsonMapper
	at org.springframework.batch.infrastructure.item.file.mapping.JsonLineMapper.<init>(JsonLineMapper.java:51)
	at LineMapperUser.main(LineMapperUser.java:5)
Caused by: java.lang.ClassNotFoundException: tools.jackson.databind.json.JsonMapper
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490)
	... 2 more

Reproducer project linked hereunder.

Expected behavior
As per the migration guide, a migration to Jackson 3 is recommended but should not be mandatory.

Minimal Complete Reproducible example
Reproducer project:

reproducer-json-line-mapper-vs-jackson-2.zip

Potentially related issue: #1207

Work around

There is a workaround by having a custom LineMapper like this:

import com.fasterxml.jackson.databind.ObjectMapper;

public class Jackson2JsonLineMapper implements LineMapper<Map<String, Object>> {
  private final ObjectMapper jsonMapper = new ObjectMapper();
  @Override
  @SuppressWarnings("unchecked")
  public Map<String, Object> mapLine(String line, int lineNumber) throws Exception {
    return this.jsonMapper.readValue(line, Map.class);
  }
}