question: private static void initializeSettings ( Settings . Builder output , Settings input , boolean loadDefaults ) { output . put ( input ) ; if ( useSystemProperties ( input ) ) { if ( loadDefaults ) { for ( String prefix : PROPERTY_DEFAULTS_PREFIXES ) { output . putProperties ( prefix , System . getProperties ( ) ) ; } } for ( String prefix : PROPERTY_PREFIXES ) { output . putProperties ( prefix , System . getProperties ( ) , PROPERTY_DEFAULTS_PREFIXES ) ; } } output . replacePropertyPlaceholders ( ) ; }
target:  Initializes the builder with the given input settings, and loads system properties settings if allowed. If loadDefaults is true, system property default settings are loaded.