OntResource (in ontapi.model) is not public

### Version

5.6.0

### What happened?

`OntResource` is not public therefore calling any methods overridden from RDFNode (E.g., `OntModel getModel()`) results in an `IllegalAccessError`.

This was experienced when building/running for Java 24/25.

### Relevant output and stacktrace

```shell

```

### Are you interested in making a pull request?

None

Start by locating the OntResource type in the ontapi.model package and reading its relationship to RDFNode and OntModel. Reproduce the reported IllegalAccessError on Java 24 or 25 if possible; done means callers can invoke overridden RDFNode methods such as OntModel getModel() without an access error.

Written by the indexing model from the issue text.