Bad error message on accidentally nested schema.

When I build a spec (here: https://gist.github.com/nicksloan/0ec7e74af30ac9540ccf) with a schema nested within a schema (see line #647) I am shown a less than helpful error message:

[main] WARN io.swagger.util.PropertyDeserializer - no property from null, null, {ENUM=null, TITLE=null, DESCRIPTION=Unexpected error, DEFAULT=null, PATTERN=null, DESCRIMINATOR=null, MIN_ITEMS=null, MAX_ITEMS=null, MIN_PROPERTIES=null, MAX_PROPERTIES=null, MIN_LENGTH=null, MAX_LENGTH=null, MINIMUM=null, MAXIMUM=null, EXCLUSIVE_MINIMUM=null, EXCLUSIVE_MAXIMUM=null, UNIQUE_ITEMS=null, EXAMPLE=null, TYPE=null, FORMAT=null, READ_ONLY=null, VENDOR_EXTENSIONS={}}

Using the online validator in debug mode is much more helpful in identifying the actual issue:

{"schemaValidationMessages":[{"level":"error","domain":"validation","keyword":"oneOf","message":"instance failed to match exactly one schema (matched 0 out of 2)","schema":{"loadingURI":"http://swagger.io/v2/schema.json#","pointer":"/definitions/responseValue"},"instance":{"pointer":"/paths/~1infomous-graph/get/responses/default"}}]}

The codegen version is 2.1.5 from Homebrew.

Start with the nested schema at line 647 of the linked gist and compare the CLI output with the online validator's debug response. Trace the warning from io.swagger.util.PropertyDeserializer and identify the validation path that produces it. Done means the malformed schema receives a more useful diagnostic than the current generic warning.