Index external additional resource properties

[tylerjmchugh]

Resources stored in cloud backends (JCloud, Azure Blob, etc.) often carry valuable metadata (e.g. ownership, department, sensitivity) directly on the storage object.

Currently, GeoNetwork completely ignores these cloud-side resource properties. While they may exist in cloud storage, any application that needs them must make direct calls to the storage backend to retrieve them.

This PR addresses this gap by allowing selected cloud storage properties to be copied into the catalogue index, enabling fast access and search without requiring additional cloud storage calls.

export JCLOUD_ADDITIONAL_INDEXED_PROPERTIES=department,owner,sensitivity

jcloud.additional.indexed.properties=department,owner,sensitivity

"filestore": [
  {
    "lastModification": "2025-12-09T18:22:36.000+00:00",
    "metadataResourceExternalManagementProperties": {
      "id": "resource-001",
      "url": "http://localhost:8080/resources/resource-001",
      "validationStatus": "INCOMPLETE",
      "additionalProperties": {
        "department": "Planning",
        "owner": "John Doe",
        "sensitivity": "Unclassified"
      }
    },
    "size": 112339,
    "url": "http://localhost:8084/catalogue/srv/api/records/37aecae5-7783-4274-b595-df02aa003ac3/attachments/Sample1.pdf",
    "version": "1",
    "visibility": "PUBLIC"
  }
]

Checklist

• I have read the contribution guidelines
• Pull request provided for main branch, backports managed with label
• Good housekeeping of code, cleaning up comments, tests, and documentation
• Clean commit history broken into understandable chucks, avoiding big commits with hundreds of files, cautious of reformatting and whitespace changes
• Clean commit messages, longer verbose messages are encouraged
• API Changes are identified in commit messages
• Testing provided for features or enhancements using automatic tests
• User documentation provided for new features or enhancements in manual
• Build documentation provided for development instructions in README.md files
• Library management using pom.xml dependency management. Update build documentation with intended library use and library tutorials or documentation