Extend code generator to support complex interface patterns in databind bindings

[david-waltermire]

Summary

The databind module contains pre-generated binding classes in gov.nist.secauto.metaschema.databind.model.metaschema.binding that have been heavily modified with:

• Custom interface implementations
• Extended base classes
• Additional helper methods

These modifications are defined in the binding configuration (databind-metaschema/src/main/metaschema-bindings/metaschema-metaschema-bindings.xml) but the current code generator doesn't fully support regenerating these classes with all customizations intact.

Current State

• Binding classes are pre-generated and checked into src/main/java
• Manual modifications have been applied post-generation
• No automated way to regenerate while preserving customizations
• Collection properties use hardcoded implementation classes (LinkedList, LinkedHashMap)

Proposed Solution

Extend the metaschema-maven-plugin code generator to support:

1. Interface and Base Class Configuration

• <implement-interface> - Add interface implementations to generated classes
• <extend-base-class> - Specify custom base classes

2. Collection Implementation Override

Support overriding the default collection implementation class for collection-typed properties via binding configuration:

<define-assembly name="test-suite">
  <define-field name="test-collections">
    <collection-class>java.util.ArrayList</collection-class>
  </define-field>
</define-assembly>

This allows:

• ArrayList instead of LinkedList for better random access performance
• TreeMap instead of LinkedHashMap for sorted key ordering
• Custom collection implementations for specialized use cases

The generator should:

1. Parse the <collection-class> element from binding configuration
2. Pass the override to getCollectionImplementationClass() in the type info
3. Fall back to current defaults (LinkedList/LinkedHashMap) when not specified
4. Validate that the specified class is compatible with the collection type (List vs Map)

Acceptance Criteria

• Code generator supports implement-interface binding configuration
• Code generator supports extend-base-class binding configuration
• Code generator supports collection-class binding configuration for collection properties
• Collection class override is validated for type compatibility (List/Map)
• Regenerated databind binding classes match current functionality
• Add pom-bootstrap.xml for databind module
• Document bootstrap process in databind README

Related

• Part of XMLBeans removal effort
• See metaschema-testing/pom-bootstrap.xml for bootstrap pattern example
• PR feat: enhance code generator Javadoc and null-safety annotations #577 implements lazy initialization infrastructure that this builds upon

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🔗 Similar Issues

Related Issues

• Enhance code generator to produce complete Javadoc for binding classes #571
• Refactor to Native Metaschema API Implementation oscal-server#32
• Support any in Java binding annotations #220
• Provide full support for choice in bound classes #262

🔗 Related PRs

metaschema-framework/liboscal-java#220 - fix: update test for metaschema-java PR #529 compatibility [merged]
#566 - feat: remove XMLBeans dependency from databind module [merged]

👤 Suggested Assignees

• david-waltermire
• wandmagic

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