'Validate properties for the resource.
Validates to ensure nothing in value_specs overwrites any key that
exists in the schema.
Also ensures that shared and tenant_id is not specified
in value_specs.'

@staticmethod
def validate_properties(properties):

    if ('value_specs' in properties):
        banned_keys = set(['shared', 'tenant_id']).union(set(properties))
        found = banned_keys.intersection(set(properties['value_specs']))
        if found:
            return ('%s    not    allowed    in    value_specs' % ',    '.join(found))
