### Question:
ConfigBuilder { @Nullable protected static Integer getIntProperty(String name, Map<String, String> map) { try { return Integer.parseInt(map.get(name)); } catch (NumberFormatException ex) { return null; } }  T readProperties(Properties properties); T readEnvironmentVariables(); T readSystemProperties();  }### Answer:
@Test void intProperty() { Integer intProperty = ConfigBuilder.getIntProperty("int", Collections.singletonMap("int", "43543")); assertThat(intProperty).isEqualTo(43543); }
@Test void invalidIntProperty() { Integer intProperty = ConfigBuilder.getIntProperty("int", Collections.singletonMap("int", "false")); assertThat(intProperty).isNull(); }
@Test void nullValue_IntProperty() { Integer intProperty = ConfigBuilder.getIntProperty("int", Collections.emptyMap()); assertThat(intProperty).isNull(); }
@Test void testIntProperty() { Map<String, String> map = new HashMap<>(); map.put("int", "1"); map.put("long", "2L"); map.put("boolt", "true"); map.put("boolf", "false"); map.put("string", "random"); assertThat(ConfigBuilder.getIntProperty("int", map)).isNotNull(); assertThat(ConfigBuilder.getIntProperty("int", map)).isEqualTo(1); assertThat(ConfigBuilder.getIntProperty("long", map)).isNull(); assertThat(ConfigBuilder.getIntProperty("boolt", map)).isNull(); assertThat(ConfigBuilder.getIntProperty("boolf", map)).isNull(); assertThat(ConfigBuilder.getIntProperty("string", map)).isNull(); assertThat(ConfigBuilder.getIntProperty("no-key", map)).isNull(); }