LANG-1711: Skip inaccessible fields in ReflectionDiffBuilder

[JeremySun0731]

This change makes ReflectionDiffBuilder skip fields that cannot be accessed via reflection
instead of failing fast with an exception.

Previously, if reflective access to a field was denied (for example due to Java 9+ module
restrictions or security constraints), the diff process would abort entirely. This prevented
producing a partial diff even when most fields were accessible.

The implementation is limited to appendFields(...), where reflection access failures are
caught and ignored. This covers IllegalAccessException on Java 8 as well as runtime reflection
failures on newer Java versions. No public APIs were changed.

This keeps full Java 8 compatibility while improving robustness on restricted environments.

Related issue: LANG-1711

[garydgregory]

Hello @JeremySun0731

• -1: There are ZERO tests in this PR.
• I think we need a comprehensive solution/proposal for the whole package, not a one-off.
• Please see and test PR Feature : Make object accessibility optional #1558 for your use case. This is a new opt-in feature for compatibility.

[JeremySun0731]

Hi @garydgregory,

Thanks for the feedback and for pointing me to PR #1558.

I understand that a localized change in ReflectionDiffBuilder is not sufficient and that a package-wide, opt-in solution is preferred.

I’ll take a look at #1558 and test it against the LANG-1711 scenario.

Thanks for the guidance.