1. Package.html is reasonable satisfactory. The Document class has moderately satisfactory comments.
2. The 6 Field related classes are largely missing class-level comments.
3. The 4 FieldSelect classes are largely missing class-level comments.
4. The 4 tools classes have moderately satisfactory comments, except for the DateTools.Resolution class.
Most of the classes are missing @see references and @since information. Some terminology and concepts need definition, such as "normalization factors" and "term vector". Method-level comments are generally satisfactory, but somewhat repetitive between classes and interfaces. An interface/abstract method should be explained once only, not repeated in each sub-class.