The CoreMap key identifying the annotation's antecedent.
The intent of this annotation is to go with words that have been
linked via coref to some other entity. For example, if "dog" is
corefed to "cirrus" in the sentence "Cirrus, a small dog, ate an
entire pumpkin pie", then "dog" would have the
This annotation is currently used ONLY in the KBP slot filling project.
In that project, "cirrus" from the example above would also have an
AntecedentAnnotation of "cirrus".
Generally, you want to use the usual coref graph annotations
Returns the type associated with this annotation. This method must
return the same class type as its value type parameter. It feels like
one should be able to get away without this method, but because Java
erases the generic type signature, that info disappears at runtime.