### Question:
FieldValueGroupExtractor implements GroupExtractor<T> { @Override public Object apply(T t) { Field field = FieldResolution.getField(t.getClass(), fieldName); return ValueResolution.getFieldValue(t, field); } FieldValueGroupExtractor(String fieldName); @Override Object apply(T t);  }### Answer:
@Test public void groupCanBeExtractedFromField() { TestData data = new TestData("GROUP"); Function<TestData, Object> groupExtractor = new FieldValueGroupExtractor<>("group"); assertEquals(data.getGroup(), groupExtractor.apply(data)); }