Pentaho Data Integration

Added HTTP response-header output to HTTP, HTTP POST, and REST Client transformation steps.

JavaETLHTTP

What I contributed

I added the ability to return HTTP response headers as output fields from the HTTP, HTTP POST, and REST Client steps in Pentaho Data Integration.

The change covered step metadata, configuration interfaces, localized messages, runtime behavior, and integration tests.

My original contribution was later incorporated through PR #2212. Both the authored commit and the integrating pull request are linked as evidence.