### Question:
ConfigBuilder { @Nullable protected static Double getDoubleProperty(String name, Map<String, String> map) { try { return Double.parseDouble(map.get(name)); } catch (NumberFormatException | NullPointerException ex) { return null; } }  T readProperties(Properties properties); T readEnvironmentVariables(); T readSystemProperties();  }### Answer:
@Test void doubleProperty() { Double doubleProperty = ConfigBuilder.getDoubleProperty("double", Collections.singletonMap("double", "5.6")); assertThat(doubleProperty).isEqualTo(5.6); }
@Test void invalidDoubleProperty() { Double doubleProperty = ConfigBuilder.getDoubleProperty("double", Collections.singletonMap("double", "something")); assertThat(doubleProperty).isNull(); }
@Test void nullValue_DoubleProperty() { Double doubleProperty = ConfigBuilder.getDoubleProperty("double", Collections.emptyMap()); assertThat(doubleProperty).isNull(); }