@Test
public void testTrimToNull() {

    final String nullString = null;
    final String emptyString = "";
    final String blankString = " ";
    final String string = " a ";
    assertThat(Strings.trimToNull(nullString), is(nullValue()));
    assertThat(Strings.trimToNull(emptyString), is(nullValue()));
    assertThat(Strings.trimToNull(blankString), is(nullValue()));
    assertThat(Strings.trimToNull(string), is("a"));
}