The specification is written as: "The keywords const and goto are reserved, even though they are not currently used".
I.e. goto - is the key word, even if unused.
Therefore, in particular, goto can not be used as an identifier, i.e. to be the name of the package, class, variable, etc.
See the original source: http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.9