Define-XML conformance validator implementing the CDISC Define-XML v2.1 Conformance Rules and the PMDA Validation Rules v6.0 Define-XML sheet against the cumba-oss-cdisc-define object model. Java only — no Python parity. LIBRARY ONLY: this module ships no CLI, matching cumba-oss-cdisc-core. It is consumed as a library; the Define-XML conformance rule corpus it evaluates is distributed separately from this artifact.