Version 2.10 null pointer on toString

[odenzo]

On Line 222 of MetaData.scala
def buildString(sb: StringBuilder): StringBuilder = {
sb append ' '
toString1(sb)
next buildString sb
}
The "next" function indicates it can return null or the next MetaData object.
Shouldn't this be checking for null value.
(e.g. Option(next).map(n => n.buildString(sb)))
I am trying to build Attributes by hand and adding null metadata and get this error.

Which is solved by setting the next to "Null" :-/