For example, user dynamically specifies what kind of entity user is interested, for example: user may be only interested in person entities, so we run opennlp.pear, but it will extract all entities, such as: person,Organization,Location,Date,Time,Money,Percentage,Parse,Chunk,Token.
This makes the extraction unnecessarily slower. Same problem happens for RegExAnnotator.pear, it is able to extract isbn, email etc, we may add our own regex to extract usa phone number or etc. But at one time, we may only want to extract email or phone number.
