Creating a Federation Execution with a `null` or empty FOM array throws NullPointerException/IndexOutOfBoundsException

[adlaws]

Attempts to create a federation execution with a null for the FOM modules parameter fail with a NullPointerException.

There are a few places in the code which cause this, depending on which version/method signature of the createFederationExecution method is invoked, but they all basically come down to an assumption that the fomModules parameter is non-null. These are...

org.portico.lrc.services.federation.msg.CreateFederation:

• 3 of the constructors need to check for a null URL (or URLs) in before processing to avoid NullPointerException

org.portico.impl.hla1516e.Rti1516eAmbassador#createFederationExecution( String federationName, URL[] fomModules, URL mimModule ):

• needs to check for null fomModules array before processing to avoid NullPointerException

org.portico.lrc.model.ModelMerger#mergeModels( List<ObjectModel> models ):

• needs to check for zero length List before processing to avoid IndexOutOfBoundsException

[adlaws]

See pull request https://github.com/openlvc/portico/pull/287 for proposed fix.