Ant Java compiling with a JDK1.4 fails with following error : 

init:
deps-clean:
clean:
init:
deps-jar:
Created dir: /home/jymen/sources/netbeans6projects/AnagramGame/AnagramGame/build/classes
Compiling 3 source files to /home/jymen/sources/netbeans6projects/AnagramGame/AnagramGame/build/classes
javac: invalid flag: -Djava.endorsed.dirs=/usr/local/netbeans-6.0m10/java1/modules/ext/jaxws21/api
Usage: javac <options> <source files>
where possible options include:
  -g                        Generate all debugging info
  -g:none                   Generate no debugging info
  -g:{lines,vars,source}    Generate only some debugging info
  -nowarn                   Generate no warnings
  -verbose                  Output messages about what the compiler is doing
  -deprecation              Output source locations where deprecated APIs are used
  -classpath <path>         Specify where to find user class files
  -sourcepath <path>        Specify where to find input source files
  -bootclasspath <path>     Override location of bootstrap class files
  -extdirs <dirs>           Override location of installed extensions
  -d <directory>            Specify where to place generated class files
  -encoding <encoding>      Specify character encoding used by source files
  -source <release>         Provide source compatibility with specified release
  -target <release>         Generate class files for specific VM version
  -help                     Print a synopsis of standard options

BUILD FAILED (total time: 0 seconds)

To reproduce the problem :
- Install jdk 1.4.2_14.
- using the sample AnagramGame netbeans project just change the properties->library->default platform from jdk 1.6 to
jkk 1.4.
- do a clean and build action and you'll get the error above.

- This is a SEVERE REGRESSION from M9 to M10 (works correctly in M9) which prevents using projects relying on JDK 1.4