This is a Kerberos-specific LoginContext CallbackHandler used to inject the default LoginContext for the Kerberos auth.
Per JavaSE javax auth API spec, this injection/override applies on the following cases (see below, ours falls in the 2nd
category):
- If the constructor has a CallbackHandler input parameter, the LoginContext uses the caller-specified CallbackHandler
object.
- If the constructor does not have a CallbackHandler input parameter, or if the caller specifies a null CallbackHandler object
(and a null value is permitted), the LoginContext queries the auth.login.defaultCallbackHandler security property for the fully
qualified class name of a default handler implementation.