question: public static String parseVolumeHostDirectory ( String volume ) { if ( StringUtils . isEmpty ( volume ) ) { return volume ; } if ( ! volume . contains ( HOST_CONTAINER_DIR_DELIMITER ) ) { return volume ; } String [ ] hostContainerDir = volume . split ( HOST_CONTAINER_DIR_DELIMITER ) ; if ( hostContainerDir . length != 2 ) { throw new IllegalArgumentException ( "Invalid volume directory." ) ; } String hostDir = hostContainerDir [ 0 ] ; return hostDir ; }
target:  Parses volume host directory only.