### Question:
ValueFilterTrim extends StringFilter { @Override public String filter(String value) { return LessStrings.isEmpty(value) ? value : value.trim(); }  @Override String filter(String value);  }### Answer:
@Test public void testTrim() { ValueFilterTrim vft = new ValueFilterTrim(); assertEquals("hi", vft.filter(" hi \t")); assertEquals(null, vft.filter((String) null)); }