DefaultPiiReplacer implements PiiReplacer { @Override public String replace(String value) { return value == null ? null : ""; }  @Override String replace(String value);  }
@Test public void fooInput() throws Exception { String result = underTest.replace("foo"); assertThat(result, is("")); }
@Test public void nullInput() throws Exception { String result = underTest.replace(null); assertThat(result, is(nullValue())); }