[Bug]: Problem with return result from subpipeline and ldap request if empty

### Apache Hop version?

2.14

### Java version?

Openjdk 17

### Operating system

Windows

### What happened?

Hello

I'm looking for a solution to preserve the dn input param if i use a ldap input step in in a subpipeline and the query results are null

If I add step A, it returns only the empty fields from the subpipeline without combining them with the columns from the base pipeline.

If the LDAP query finds data, then I have the pipeline columns combined with the subpipeline columns.

Test Pipeline

Test Subpipeline

Thx

### Issue Priority

Priority: 3

### Issue Component

Component: Pipelines

Start by reproducing the described Test Pipeline and Test Subpipeline with the LDAP input step on Apache Hop 2.14, using the stated Java and Windows environment. The fix is complete when an empty LDAP result preserves the DN input and combines the base-pipeline columns with the subpipeline columns, matching the behavior when data is found.

Written by the indexing model from the issue text.