@NonNull
  @Override
  public EntityStatementJWS fetchFederationStatement(
      URI federationFetchUrl, String issuer, String subject) {
    var key = "%s|%s|%s".formatted(federationFetchUrl, issuer, subject);
    return federationStatementCache.computeIfAbsent(
        key, k -> delegate.fetchFederationStatement(federationFetchUrl, issuer, subject));
  }
@Test
  void fetchFederationStatement() {

    var url = URI.create("https://example.com");
    var iss = "myiss";
    var sub = "mysub";

    var expected = new EntityStatementJWS(null, null);

    when(delegate.fetchFederationStatement(url, iss, sub)).thenReturn(expected);

    // when
    var got = sut.fetchFederationStatement(url, iss, sub);

    // then
    verify(delegate).fetchFederationStatement(url, iss, sub);
    assertEquals(expected, got);
  }