Adds a mechanism specific credential-element to an existing credential. This method allows the construction of credentials, one mechanism at a time.

This routine is envisioned to be used mainly by context acceptors during the creation of acceptor credentials which are to be used with a variety of clients using different security mechanisms.

This routine adds the new credential element "in-place". To add the element in a new credential, first call clone to obtain a copy of this credential, then call its add method.

As always, GSS-API implementations must impose a local access-control policy on callers to prevent unauthorized callers from acquiring credentials to which they are not entitled. Non-default values for initLifetime and acceptLifetime cannot always be honored by the underlying mechanisms, thus callers should be prepared to call getRemainingInitLifetime(Oid) and getRemainingAcceptLifetime(Oid) on the credential.

Parameters:

name     the name of the principal for whom this credential is to be acquired. Use null to specify the default principal.

initLifetime     the number of seconds that the credential element should remain valid for initiating of security contexts. Use GSSCredential.INDEFINITE_LIFETIME to request that the credentials have the maximum permitted lifetime for this. Use GSSCredential.DEFAULT_LIFETIME to request default credential lifetime for this.

acceptLifetime     the number of seconds that the credential element should remain valid for accepting security contexts. Use GSSCredential.INDEFINITE_LIFETIME to request that the credentials have the maximum permitted lifetime for this. Use GSSCredential.DEFAULT_LIFETIME to request default credential lifetime for this.

mech     the mechanism over which the credential is to be acquired.

usage     the usage mode that this credential element should add to the credential. The value of this parameter must be one of: INITIATE_AND_ACCEPT, ACCEPT_ONLY, and INITIATE_ONLY.

Exceptions:

GSSException containing the following major error codes: GSSException.DUPLICATE_ELEMENT, GSSException.BAD_MECH, GSSException.BAD_NAMETYPE, GSSException.NO_CRED, GSSException.CREDENTIALS_EXPIRED, GSSException.FAILURE

`name`		the name of the principal for whom this credential is to be acquired. Use `null` to specify the default principal.
`initLifetime`		the number of seconds that the credential element should remain valid for initiating of security contexts. Use `GSSCredential.INDEFINITE_LIFETIME` to request that the credentials have the maximum permitted lifetime for this. Use `GSSCredential.DEFAULT_LIFETIME` to request default credential lifetime for this.
`acceptLifetime`		the number of seconds that the credential element should remain valid for accepting security contexts. Use `GSSCredential.INDEFINITE_LIFETIME` to request that the credentials have the maximum permitted lifetime for this. Use `GSSCredential.DEFAULT_LIFETIME` to request default credential lifetime for this.
`mech`		the mechanism over which the credential is to be acquired.
`usage`		the usage mode that this credential element should add to the credential. The value of this parameter must be one of: `INITIATE_AND_ACCEPT`, `ACCEPT_ONLY`, and `INITIATE_ONLY`.