question: public static String modifyDrmFwLockFileExtension ( String filename ) { if ( filename != null ) { int extensionIndex ; extensionIndex = filename . lastIndexOf ( "." ) ; if ( extensionIndex != - 1 ) { filename = filename . substring ( 0 , extensionIndex ) ; } filename = filename . concat ( EXTENSION_INTERNAL_FWDL ) ; } return filename ; }
target:  Modifies the file extension for a DRM Forward Lock file NOTE: This function shouldn't be called if the file shouldn't be DRM converted