XMLEventFactory.createStartDocument(null, "1.0") will generate <?xml version="1.0"?> correctly on solaris-sparc.
But on linux-i586, it generates <?xml version="1.0" encoding="UTF-8"?> and the default encode is set as utf-8.

It looks the encoding is wrong on linux-i586 since we set is as null.

The Test.java has been attached.

log on linux-i586:
=================
gtee@jsn-gtwy-1: ~ $ echo $JAVA_HOME
/net/sqenfs-1/export1/jdk/re/8/promoted/latest/binaries/linux-i586
gtee@jsn-gtwy-1: ~ $ pwd
/net/sqenfs-1/export1/comp/jsn/users/patrick
gtee@jsn-gtwy-1: ~ $ $JAVA_HOME/bin/javac Test.java
gtee@jsn-gtwy-1: ~ $ $JAVA_HOME/bin/java Test
<?xml version="1.0" encoding="UTF-8"?><root></root>
=================

log on solaris-sparc:
=================
gtee@jsn-sb2500-5: ~ $ echo $JAVA_HOME
/net/sqenfs-1/export1/jdk/re/8/promoted/latest/binaries/solaris-sparc
gtee@jsn-sb2500-5: ~ $ $JAVA_HOME/bin/javac Test.java
gtee@jsn-sb2500-5: ~ $ $JAVA_HOME/bin/java Test
<?xml version="1.0"?><root></root>
=================