Imports google.golang.org/appengine github.com/dgrijalva/jwt-go cloud.google.com/go/kms/apiv1 github.com/patrickmn/go-cache github.com/pquerna/cachecontrol google.golang.org/api/iamcredentials/v1 google.golang.org/genproto/googleapis/cloud/kms/v1 Standard library imports crypto/rsa encoding/pem crypto crypto/sha1 encoding/asn1 context crypto/x509 encoding/base64 encoding/json errors fmt io/ioutil math/big net/http strings sync time