ShadowString, ShadowThread: get rid of overriden hashCode() and equals() and rely on the superclass implementation that only cares about net reference equality.
ShadowObject, ShadowString, ShadowThread: make a shadow object updatable from other object with the same net reference (required for partially-constructed special objects).
ShadowString, ShadowThread: get rid of setter methods in favor of updateFrom() method.
ShadowThread: make additional information about a thread atomically updateable.
ShadowClassTable: log when the JAVA_LANG_CLASS reference is updated.
ShadowClassTable, ShadowObjectTable: make the classes final.
ShadowObjectTable: use the updateFrom() method from shadow object instead of hand-coding updates in the registration method.
ShadowObjectTable: simplify the get() method by extracting code to create shadow objects in conjunction with the use of computeIfAbsent() method on the shadow object map.