Some packages on OSses install a JRE by default in /usr/lib/jvm/default-java. Openfire should consider this location.
If JAVA_HOME is not set openfire.init.d now searches for Java in these locations:
/usr/lib/jvm/default-java
/usr/lib/jvm/java-7-sun
/usr/lib/jvm/java-6-sun
/usr/lib/jvm/java-1.5.0-sun
/usr/lib/jvm/java-7-openjdk-amd64
/usr/lib/jvm/java-7-openjdk
/usr/lib/jvm/java-6-openjdk-amd64
/usr/lib/jvm/java-6-openjdk