question: public static Map < URI , Integer > filterVolumeMap ( Map < URI , Integer > volumeMap , Set < URI > includedVolumes ) { Map < URI , Integer > result = new HashMap < URI , Integer > ( ) ; if ( includedVolumes == null ) { return result ; } for ( URI includedVolume : includedVolumes ) { result . put ( includedVolume , volumeMap . get ( includedVolume ) ) ; } return result ; }
target:  Filter the volumeMap to only contain the desired includedVolumes.