func (t *OAuth2Tripper) Credentials() *common.Credentials {
	return t.credentials
}
Credentials returns the credentials associated with this OAuth2Tripper
package oauth2
import (
	"github.com/stretchr/gomniauth/common"
	"net/http"
)
type OAuth2Tripper struct {
	underlyingTransport http.RoundTripper
	credentials         *common.Credentials
	provider            common.Provider
}
func NewOAuth2Tripper(creds *common.Credentials, provider common.Provider) *OAuth2Tripper {
	return &OAuth2Tripper{common.GetRoundTripper(), creds, provider}
}
func (t *OAuth2Tripper) RoundTrip(req *http.Request) (*http.Response, error) {
	if t.Credentials() != nil {
		req = cloneRequest(req)
		headerK, headerV := AuthorizationHeader(t.Credentials())
		req.Header.Set(headerK, headerV)
		req.Header.Set("Accept", "application/json")
	}
	return t.underlyingTransport.RoundTrip(req)
}