| ClassDescriptor | Contract describing the information Hibernate needs in terms of instrumenting a class, either via ant task or dynamic classloader. |
| ClassFilter | Used to determine whether a class should be instrumented. |
| FieldFilter | Used to determine whether a field reference should be instrumented. |
| BasicClassFilter | BasicClassFilter provides class filtering based on a series of packages to be included and/or a series of explicit class names to be included. |
| ByteCodeHelper | A helper for reading byte code from various input sources. |