@Test
  public void setsFilterGivenBlankPattern()
      throws ClassNotFoundException, IllegalAccessException, InvocationTargetException,
      NoSuchMethodException {
    ObjectInputFilterApi api = new ReflectiveObjectInputFilterApi(apiPackage);
    Object filter = api.createFilter(" ");

    api.setSerialFilter(filter);

    assertThat(api.getSerialFilter())
        .as("ObjectInputFilter$Config.getSerialFilter()")
        .isSameAs(filter);
  }
This test calls the real setSerialFilter which can only be set once within a JVM, so it's in an
integration test which forks a new JVM for the test class.
geode-serialization/src/integrationTest/java/org/apache/geode/internal/serialization/filter/ReflectiveObjectInputFilterApiSetFilterBlankIntegrationTest.java