Reading http://docs.oracle.com/javase/7/docs/api/java/util/Properties.html#load(java.io.Reader) and trying to create a challenge properties file for your Java properties-file parser

hell.properties

# this is a comment. see
# http://docs.oracle.com/javase/7/docs/api/java/util/Properties.html#load(java.io.Reader)
! this too. and empty lines are allowed


     # this is an space-indented comment
	  #this is a tab-indented and space-indented comment

# key separators include any unescaped "=", ":" or ws.
key1=value
key2 value
key3:value
# preceeding ws in values are ignored (just as with multiline values)
key4    =   value


         ! this is a comment too (yes it is!)

# you can escape stuff with \

e\=mc2=yes
key2=value with multiple words

# add line terminator
multiline_string=one\ntwo

#################### multiline values ####################

# you can escape newline in values like this:
multiline_again=one \
                    two \
                    three
# all but one whitespace before "two" and "three" should be ignored. 
# should yield "one two three".

multiline_no_ws=motor\
        cycle
# should yield "motorcycle"

#this is allowed:
valueless
# and should yield key valueless to have the string "".


# there, easy. this is tricky part, don't escape this:
non_multiline=one\\
# that should give us the string "one" with a single backslash \
back_to_multiline=one\\\
        two

# comment indicator must be *first* non-ws character:
key=value#with#hash#signs
# should yield value "value#with#hash#signs"

# you can also create unicode characters:
# \u0020 is space " "
foo\u0020bar\u0020=\u0020barefoot
# should yield key "foo bar ", value " barefoot"

#comment that does not end with newline, but #!eof :)