oh my good, a nasty trap !!!! designed by SAP.
and a lock at google search shows, i am not the first one to fail on this
what has happened:
my fault was to use the SAP default value for the target directory
when extracting the 4 packages of downloaded files.
when downloading the (in my case) 4 packages of components
- abap installation (2 files)
- abap upgrade (4 files)
- java (5 files)
- language (4 files)
1. extracting the abap-installation files, the SAP default-value for directory is 51043228,
for example extract in c:\NW731\ the self-extracting archive creates a directory c:\NW731\51043228\ and stores the content in it.
2. extracting the abap-upgrade files, the SAP default-value for directory is again 51043228,
for example extract in c:\NW731\ the self-extracting archive creates a directory c:\NW731\51043228\ and stores the content in it (and as i know now 
, overrides some content of the first extraction. e.g. the MID.xml file in c:\NW731\51043228\ ) 
and so on ....
extracting all self-extracting archive in the same (SAP default) directory overrides everytime the MID.xml file in c:\NW731\51043228\
so last i did the language pack extraction and this overrides the MID.xml file in c:\NW731\51043228\ from java-extraction.
and that is the point, why SUM Java Upgrade did not find the Java content in the c:\NW731\51043228\ directory !!! - because SUM only looks first in MID.xml !!!
who had designed this concept by SAP ? - using the same default directory-name and using for some files every time the same name e.g. MID.xml but with different content?
this person should be beaten every day for 2 hours (for the next 3 years)
This is totally disappointing and frustrating and it costs me about several hours of my short live
and it costs valuable time in our upgrade-planing.
(what the competition would say about such long upgrade times (several weeks) and upgrade efforts)
so, you have to extract several different download components in different directorys !!!