public DefaultCredentialRetrievers setCredentialHelper(@Nullable String credentialHelper) {
    this.credentialHelper = credentialHelper;
    return this;
  }
Sets the known credential helper. May either be a path to a credential helper executable, or a
credential helper suffix (following {@code docker-credential-}).

@param credentialHelper the path to a credential helper, or a credential helper suffix
    (following {@code docker-credential-}).
@return this
jib-plugins-common/src/main/java/com/google/cloud/tools/jib/plugins/common/DefaultCredentialRetrievers.java