### Question:
UndefinedTypeConverter implements TypeConverter { @Override public String toString(Type type, Object value) { return StringTypeConverter.NULL_LITERAL; }  @Override boolean isApplicable(Type type); @Override Object fromString(Type type, String value); @Override String toString(Type type, Object value);  }### Answer:
@Test void shouldReturnNullLiteralWhenToStringConversion() { String converted = converter.toString(null, null); assertThat(converted).isEqualTo(StringTypeConverter.NULL_LITERAL); }