api: Fix MempoolUTxOInput address field from Text to Maybe Text

Closes #83

Author: sorki

blockfrost-api/CHANGELOG.md

@@ -1,5 +1,8 @@
 # Version [next](https://github.com/blockfrost/blockfrost-haskell/compare/api-0.14.0.0...master) (2025-MM-DD)
 
+* Changes
+  * Fix `MempoolUTxOInput` `address` field from `Text` to `Maybe Text` [#83](https://github.com/blockfrost/blockfrost-haskell/issues/83) [#84](https://github.com/blockfrost/blockfrost-haskell/issues/84)
+
 # Version [0.14.0.0](https://github.com/blockfrost/blockfrost-haskell/compare/api-0.13.0.0...api-0.14.0.0) (2025-12-02)
 
 * Changes

blockfrost-api/src/Blockfrost/Types/Cardano/Mempool.hs

@@ -47,7 +47,7 @@ data TransactionInMempool = TransactionInMempool
   via CustomJSON '[FieldLabelModifier '[StripPrefix "_transaction", CamelToSnake]] TransactionInMempool
 
 data MempoolUTxOInput = MempoolUTxOInput
-   { _address :: Text -- ^ Address
+   { _address :: Maybe Text -- ^ Address
    , _txHash :: Text -- ^ Transaction hash
    , _outputIndex :: Integer -- ^ Output index
    , _collateral :: Bool -- ^ True if the input is a collateral input