question: public static void saveSignatureChecksums ( List units , ApplicationData data , flex2 . compiler . common . Configuration config ) { if ( ! config . isSwcChecksumEnabled ( ) ) { data . swcDefSignatureChecksums = null ; return ; } if ( units != null ) { data . swcDefSignatureChecksums = new HashMap < QName , Long > ( ) ; for ( Iterator iter = units . iterator ( ) ; iter . hasNext ( ) ; ) { CompilationUnit unit = ( CompilationUnit ) iter . next ( ) ; Source source = unit == null ? null : unit . getSource ( ) ; if ( source != null && source . isSwcScriptOwner ( ) && ! source . isInternal ( ) ) { addSignatureChecksumToData ( data , unit ) ; } } } }
target:  Save the compiler units signature checksums to ApplicationData. These will be used by the next compilation to determine if we can do an incremental compiler or if a full recompilation is required.