XML parsing errors for external constraints with nested contexts

[aj-stein-nist]

Describe the bug

While pairing on the creation of example models to demonstrate the usage of constraint let variable bindings and its implications, we ran into some where example external constraint modules were not parsing with XML correctly for nested context assemblies. I am reporting this bug and adding integration tests to help perform root cause analysis and fix a bug.

Who is the bug affecting?

Developers using the Java libraries or metaschema-cli to process external constraints and validate document instance(s) with them.

What is affected by this bug?

Deserializing and procssing externalized metaschema constraints.

When does this occur?

Consistently.

How do we replicate the issue?

1. Use the referenced examples.
2. Run the following commands, see the version info about the development build, commands, and sample files in this Gist: https://gist.github.com/aj-stein-nist/b676708701902c54770c2bacad8c2ce9.

Expected behavior (i.e. solution)

The processor properly validates valid document instances but also properly outputs relevant messages about relevant errors.

Other Comments

N/A