Generated code to support adding values to lists

[regnosys]

Generated code to support adding values to lists

[jim-h-wang]

@dhuebner

We have not yet implemented the below into the object code generators (so generated code that assigns lists is still broken):

public EventBuilder addParty(List<Party> party) {
            if(this.party == null){
                this.party = new ArrayList<>();
            }
            for (Party aprtyToAdd : party) {
                this.party.add(aprtyToAdd.toBuilder());
            }
            return this;
        }

[dhuebner]

@jim-h-wang Can we close it?

[dhuebner]

Works in #62

[dhuebner]

One part is still missing:

assign-output reset -> before -> updatedContract 
-> contractualProduct -> economicTerms -> payout -> equityPayout[2] :

Should add an entry at index 2

resetHolder
  .getOrCreateBefore().getOrCreateUpdatedContract().getOrCreateContractualProduct()
     .getOrCreateEconomicTerms().getOrCreatePayout()
		.addEquityPayout(MapperS.of(equityPayout).get(), 2);

We do not support indexed adding in the Builder API

[dhuebner]

@jim-h-wang Should equityPayout[2] : xyz replace an element at index 2 or just add a new?

[jim-h-wang]

@dhuebner
Replace if it already exists, add a new one if not.