func (r *resolver) MergeCredentials(creds ...*AwsCredentials) *AwsCredentials {
	if r.creds == nil {
		r.creds = r.defCreds
	}
	r.creds.MergeIn(creds...)
	return r.creds
}
MergeCredentials sets additional credentials for the resolver, and returns th updated credentials.
For best effect, use after calling Credentials().
package config
import "github.com/mmmorris1975/aws-runas/shared"
type resolver struct {
	loader     Loader
	defConfig  *AwsConfig
	defCreds   *AwsCredentials
	config     *AwsConfig
	creds      *AwsCredentials
	resolveSrc bool
}
func NewResolver(loader Loader, resolveSrc bool) *resolver {
	return &resolver{
		loader:     loader,
		defConfig:  new(AwsConfig),
		defCreds:   new(AwsCredentials),
		resolveSrc: resolveSrc,
	}
}
func (r *resolver) WithLogger(l shared.Logger) *resolver {
	logger = l  
	return r
}
func (r *resolver) WithDefaultConfig(config *AwsConfig) *resolver {
	if config != nil {
		r.defConfig = config
	}
	return r
}
func (r *resolver) WithDefaultCredentials(creds *AwsCredentials) *resolver {
	if creds != nil {
		r.defCreds = creds
	}
	return r
}
func (r *resolver) MergeConfig(cfg ...*AwsConfig) *AwsConfig {
	if r.config == nil {
		r.config = r.defConfig
	}
	r.config.MergeIn(cfg...)
	return r.config
}