@Override
  public boolean isInstalled(String coreExtensionName) {
    checkInitialized();

    return installedCoreExtensions.stream()
      .anyMatch(t -> coreExtensionName.equals(t.getName()));
  }
@Test
  public void isInstalled_fails_with_ISE_if_called_before_setLoadedCoreExtensions() {
    assertThatThrownBy(() -> underTest.isInstalled("foo"))
      .isInstanceOf(IllegalStateException.class)
      .hasMessage("Repository has not been initialized yet");
  }