Extract annotations validation to a single class.

Format code according to JUnit's code style.

Use nested classes for FieldComparator and MethodComparator.

Changed AnnotatableValidator from enum to abstract class.

Make map final and use upper case for constant.

Extract createTreeSetWithMapValues(...). DRY.

Add Javadoc and use Generics for AnnotatableValidator.

Added @since 4.12 to new methods.

Avoid @SuppressWarnings.

Removed unmodifiableList, because Arrays.asList ist unmodifiable, too.

Use Lists instead of Collections. (Apply code review.)

Use Lists instead of Collections. (Apply code review.)

Restore makeDeeplyUnmodifiable. (Apply code review.)

Don't sort fields twice.

Add missing spaces.