[osmosis-dev] Osmosis and empty roles

[marcus.wolschon at googlemail.com]

Hello Brett,

I found that some http-based services return relation-members with no
"role"-tag if it's empty.
Osmosis would parse these and create a null role without complaining.
Later this causes all kinds of problems as the role-attribute is not
supposed to ever be null.

I added a check in the constructor of RelationMember to disallow
the creation of such members in the first place and patched
the RelationMemberEntityHandler to threat a missing "role"-tag
as an empty role.

This seems to fix the issue with the NullPointerException that
makes osmosis create invalid osc-files.

Marcus