### Question:
StringToIntegerConverter implements StringConverter<Integer> { @Override public Integer convert(String source) { return isNotEmpty(source) ? valueOf(source) : null; }  @Override Integer convert(String source); @Override int getPriority();  }### Answer:
@Test public void testConvert() { assertEquals(Integer.valueOf("1"), converter.convert("1")); assertNull(converter.convert(null)); assertThrows(NumberFormatException.class, () -> { converter.convert("ttt"); }); }