EDIT

The first line of almost each java code file is a special place holder '// $Id$' which was meant to be replaced by the svn revision number.
This is no longer useful and should be removed.

The removal of the lines in question has been done with the following scripts:

code-cleanup.sh

#!/bin/bash

TMPF=cleanup.tmp
FILE_PATTERN="*.java" # inc|module|install|php|info)"
TARGED_FOLDER=$1

find $1 -type f -name "$FILE_PATTERN" -not -path '*/.*'  -exec bash -c './svn-prop-remove.awk $1 > cleanup.tmp && mv cleanup.tmp $1' - {} \;

svn-prop-remove.awk

#!/usr/bin/awk -f 
BEGIN {
}
NR==1 && $0 !~ /^\/\/ \$Id/ {print $0}
NR>1 {print $0}