Improve exception reporting for null values on optional field values

[aj-stein-gsa]

User Story

As a developer using this library and related tooling, when encountering an optional field value, I would like a more precise error message and controlled error behavior when such a null value is visited. I do not want a null pointer exception.

NOTE: This is a fix in the core library that is the root cause of the bug reported in https://github.com/GSA/fedramp-automation/issues/787.

Goals

• [ ] Improve error handling for users of metaschema-java based tools
• [ ] Gracefully fail in the occurrence of null values for a fireld

Dependencies

N/A

Acceptance Criteria

• [ ] All website and readme documentation affected by the changes in this issue have been updated.
• [ ] A Pull Request (PR) is submitted that fully addresses the goals of this User Story. This issue is referenced in the PR.
  • [ ] Remove the ObjectUtils.requireNonNull() check on https://github.com/metaschema-framework/metaschema-java/blob/ebdf350362e3c75f2fb39969a407089464a9b7c0/databind/src/main/java/gov/nist/secauto/metaschema/databind/model/IBoundDefinitionModelFieldComplex.java#L77 and other applicable areas in the code base.
  • [ ] Properly implement null-checking and throw the correct exception type in place of the NPE generated from the replaced null check above
  • [ ] Implement tests to check for correctness of implementation and gaps as approprriate
• [ ] The CI-CD build process runs without any reported errors on the PR. This can be confirmed by reviewing that all checks have passed in the PR.

Revisions

No response

[aj-stein-gsa]

@david-waltermire do we need to wrap this into the upcoming release? I do not know if we are planning that for the next day or two or we have some wiggle room. Let me know, thanks.