10. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a data processing system, causes the data processing system to: generate a candidate answer to an input question using a natural language processing of the input question and a corpus of information from which the candidate answer is identified; select a validator to apply to the candidate answer based on a characteristic of a correct answer for the input question; apply the validator to the candidate answer to evaluate whether or not one or more criteria of the validator are satisfied by the candidate answer; generate validation information based the evaluation of whether or not criteria of the validator are met by the candidate answer; and store the validation information in a validation status object associated with the input question, wherein the validator is one of a plurality of validators registered with a pluggable validator framework, and wherein registration of the validator with the pluggable validator framework comprises specifying for which answer type or answer extension type in an answer key data structure the validator corresponds to.
10. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a data processing system, causes the data processing system to: generate a candidate answer to an input question using a natural language processing of the input question and a corpus of information from which the candidate answer is identified; select a validator to apply to the candidate answer based on a characteristic of a correct answer for the input question; apply the validator to the candidate answer to evaluate whether or not one or more criteria of the validator are satisfied by the candidate answer; generate validation information based the evaluation of whether or not criteria of the validator are met by the candidate answer; and store the validation information in a validation status object associated with the input question, wherein the validator is one of a plurality of validators registered with a pluggable validator framework, and wherein registration of the validator with the pluggable validator framework comprises specifying for which answer type or answer extension type in an answer key data structure the validator corresponds to. 12. The computer program product of claim 10 , wherein the candidate answer comprises a wrapper having context information for the candidate answer, and wherein the validator operates on the context information in the wrapper of the candidate answer to determine if the one or more criteria of the validator are satisfied.