chore: fixed assets and multi assets removal in case of a non modifiable list

Author: nemo83

transaction-spec/src/main/java/com/bloxbean/cardano/client/transaction/spec/Value.java

@@ -16,6 +16,8 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import static com.bloxbean.cardano.client.common.CardanoConstants.LOVELACE;
 
@@ -214,13 +216,24 @@ public Value subtract(Value that) {
         BigInteger sumCoin = (getCoin() == null ? BigInteger.ZERO.subtract(that.getCoin()) : getCoin().subtract(that.getCoin()));
         List<MultiAsset> difMultiAssets = MultiAsset.subtractMultiAssetLists(getMultiAssets(), that.getMultiAssets());
 
-        //Remove all asset with value == 0
-        difMultiAssets.forEach(multiAsset ->
-                multiAsset.getAssets().removeIf(asset -> BigInteger.ZERO.equals(asset.getValue())));
-        //Remove multiasset if there's no asset
-        difMultiAssets.removeIf(multiAsset -> multiAsset.getAssets() == null || multiAsset.getAssets().isEmpty());
-
-        return Value.builder().coin(sumCoin).multiAssets(difMultiAssets).build();
+        List<MultiAsset> filteredMultiAssets = difMultiAssets
+                .stream()
+                .flatMap(multiAsset -> {
+                    List<Asset> assets = multiAsset
+                            .getAssets()
+                            .stream()
+                            .filter(asset -> !asset.getValue().equals(BigInteger.ZERO))
+                            .collect(Collectors.toList());
+                    if (!assets.isEmpty()) {
+                        multiAsset.setAssets(assets);
+                        return Stream.of(multiAsset);
+                    } else {
+                        return Stream.empty();
+                    }
+                })
+                .collect(Collectors.toList());
+
+        return Value.builder().coin(sumCoin).multiAssets(filteredMultiAssets).build();
     }
 
     /**

transaction-spec/src/test/java/com/bloxbean/cardano/client/transaction/spec/ValueSpecTest.java

@@ -519,7 +519,7 @@ public void addSingleTokenUnit() {
         String policyId = "ef76f6f0b3558ea0aaad6af5c9a5f3e5bf20b393314de747662e8ce9";
         BigInteger hundredMil = BigInteger.valueOf(100_000_000L);
         Value value = Value.builder().coin(BigInteger.valueOf(10_000_000L)).build();
-        Value actual = value.add("ef76f6f0b3558ea0aaad6af5c9a5f3e5bf20b393314de747662e8ce9.506f6c795065657237353436", hundredMil);
+        Value actual = value.add("ef76f6f0b3558ea0aaad6af5c9a5f3e5bf20b393314de747662e8ce9506f6c795065657237353436", hundredMil);
 
         Value expected = value
                 .toBuilder()
@@ -679,7 +679,7 @@ public void amountOfMissingTokenFromUnitIsZero() {
         value = value.add(policyId, "0x506f6c795065657237353436", hundredMil);
         String assetName = new String(HexUtil.decodeHexString("506f6c795065657237353436"));
         value = value.add(policyId, assetName, hundredMil);
-        BigInteger actual = value.amountOf("4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd.546f6b68756e");
+        BigInteger actual = value.amountOf("4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd546f6b68756e");
         Assertions.assertEquals(BigInteger.ZERO, actual);
     }
 
@@ -724,10 +724,10 @@ public void isPositiveAdaOnlyParametric(String amount, boolean outcome) {
 
     @ParameterizedTest
     @CsvSource({
-            "0,4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd.546f6b68756e,1000000,true",
+            "0,4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd546f6b68756e,1000000,true",
             "0,4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd546f6b68756e,-1000000,false",
             "-1000000,4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd546f6b68756e,1000000,false",
-            "-1000000,4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd.546f6b68756e,-1000000,false",
+            "-1000000,4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd546f6b68756e,-1000000,false",
             "1000000,4247d5091db82330100904963ab8d0850976c80d3f1b927e052e07bd546f6b68756e,0,true",
     })
     public void isPositiveParametric(String lovelace, String unit, String tokenAmount, boolean outcome) {