expect 0 outputs when ProposalState is consumed

[shun-tak]

currently, it outputs 1 ProposalState when consuming but it is useless after consumed.

why don't we change it not to produce the output state?

cordage/cross-chain-atomic-swap-cordapp/src/main/kotlin/jp/co/layerx/cordage/crosschainatomicswap/contract/ProposalContract.kt

Line 42 in 1ee72aa

"An Proposal Consume transaction should create only one output proposal state." using (tx.outputsOfType<ProposalState>().size == 1)

This improvement affects CustomValidatingNotaryFlow.

cordage/cross-chain-atomic-swap-cordapp/src/main/kotlin/jp/co/layerx/cordage/crosschainatomicswap/notary/CustomValidatingNotaryFlow.kt

Line 75 in 4821768

val finalizedProposalState = stx.tx.outputsOfType<ProposalState>().single()