Use nullness checker plugin.
SearchResultImpl is null-safe.
PatisNumber and HasString are null-safe.
ResultDocument is null-safe.
LocalLuceneSearcher is null-safe.
ClassMap is null-safe.
ClassMap states conditional NonNull-ness.
Refactor ClassTable into separate class.
Fix exception message.
- Map–Set-Tables with Void values.
- Accept subclasses of TOuterKey and TInnerKey.
- add getMatchingStoredKey(outer, inner).
Refactor DynamicAdapter.applyModifier.

- DynamicAdapter.applyModifier was hard to understand, the new ModifierApplier is easier to understand.
PatisReader is null-safe.
PatisCvsReader is null-safe.
PatisExpectedEmdReader is null-safe.
QueryDisplay is null-safe.
QueryProviderRegistry is null-safe.
MediaType is null-safe.

- Change '@Nullable'-comments into annotations.
ParseTreeToObjectAdapter is null-safe.