Odd behaviour when mapping object property restrictions into the spec (UNION)

[dgarijo]

When I parse through the openapi.yaml file it isn't generating a complete schema from object properties correctly. E.g. allocatedBy has a range restriction ''Intellectual Property' or Organization or Person or System' but only Organization comes through in the openapi spec, even though it should conform to the mapping spec.

issue raised by @DougalW in #140