clearToken
Clears the currently stored authentication credentials from the cache.
This method should be called in the following cases:
When the credentials have been updated and need to take effect
When you want to force re-authentication
When you want to clear sensitive authentication data
Note: The result of credentials invocation is cached internally by default. Calling this method will force the next authentication attempt to fetch fresh credentials.
If BasicAuthConfig.cacheTokens is set to false, this method has no effect as credentials are not cached.