### Question:
ConfigurationProperties { static String buildPropertyKey(String propertyName, String[] prefixParts) { return buildPropertyKey(propertyName, Strings.UNDERSCORE, prefixParts); } private  ConfigurationProperties();   }### Answer:
@Test public void testBuildPropertyKey() { assertEquals("org.trimou.engine.config.myPropertyName", ConfigurationProperties.buildPropertyKey("MY_PROPERTY_NAME", new String[] { ConfigurationPropertiesTest.class .getPackage().getName() })); assertEquals("org.trimou.engine.config.myPropertyName", ConfigurationProperties.buildPropertyKey("MY.PROPERTY.NAME", ".", new String[] { ConfigurationPropertiesTest.class .getPackage().getName() })); }