code: SamlIdentityProviderConfig build(CredentialResolverAdapter credentialResolver) {
          checkState(entityId != null, "entity ID of the identity provider is not set");
  
          // Use the entityId as a default key name.
          final Credential signing = credentialResolver.apply(firstNonNull(signingKey, entityId));
          final Credential encryption = credentialResolver.apply(firstNonNull(encryptionKey, entityId));
  
          return new SamlIdentityProviderConfig(entityId,
                                                signing,
                                                encryption,
                                                ssoEndpoint,
                                                sloReqEndpoint,
                                                sloResEndpoint,
                                                acsEndpoint,
                                                nameIdPolicy);
      }
docs: Builds a {@link SamlIdentityProviderConfig}.