Check for presence of conditionally required fields (OpenFIX)

We are filing this because of a failing OpenFIX test, but we actually believe that the test itself is broken, so I won't describe the interaction here.

It would be nice if QuickFIX/J could check for the presence of conditionally required fields in messages when doing validation with a data dictionary. An example: In an execution report, we have the following description of ExpireDate and ExpireTime:

432 ExpireDate C Conditionally required if TimeInForce (59) = GTD and ExpireTime (126) is not specified.
126 ExpireTime C Conditionally required if TimeInForce (59) = GTD and ExpireDate (432) is not specified.

QuickFIX/J should reject a message if 59=6 but the message is missing both 432 and 126.

Other than that, this request is pretty open-ended. Clearly there would need to be some language for expressing these conditional requirements in the data dictionary, but we would have to think about what that would look like.