diff --git a/src/main/java/com/sparrowwallet/hummingbird/LegacyURDecoder.java b/src/main/java/com/sparrowwallet/hummingbird/LegacyURDecoder.java
index 2e83c10..88f32d3 100644
--- a/src/main/java/com/sparrowwallet/hummingbird/LegacyURDecoder.java
+++ b/src/main/java/com/sparrowwallet/hummingbird/LegacyURDecoder.java
@@ -83,23 +83,21 @@ public class LegacyURDecoder {
         String[] components = fragment.split("/");
 
         switch(components.length) {
-            case 2 -> {
+            case 2:
                 return new UR(components[0].substring(UR.UR_PREFIX.length() + 1), BC32.decode(components[1]));
-            }
-            case 3 -> {
+            case 3:
                 String digest = components[1];
                 String data = components[2];
                 checkDigest(data, digest);
                 return new UR(components[0].substring(UR.UR_PREFIX.length() + 1), BC32.decode(data));
-            }
-            case 4 -> {
+            case 4:
                 checkAndGetSequence(components[1]);
-                String digest = components[2];
-                String data = components[3];
-                checkDigest(digest, fragment);
-                return new UR(components[0].substring(UR.UR_PREFIX.length() + 1), BC32.decode(data));
-            }
-            default -> throw new IllegalArgumentException("Invalid number of fragments: expected 2 / 3 / 4 but got " + components.length);
+                String seqDigest = components[2];
+                String seqData = components[3];
+                checkDigest(seqDigest, fragment);
+                return new UR(components[0].substring(UR.UR_PREFIX.length() + 1), BC32.decode(seqData));
+            default:
+                throw new IllegalArgumentException("Invalid number of fragments: expected 2 / 3 / 4 but got " + components.length);
         }
     }
 
diff --git a/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainDecoder.java b/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainDecoder.java
index 12e8c23..59b11e7 100644
--- a/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainDecoder.java
+++ b/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainDecoder.java
@@ -266,7 +266,9 @@ public class FountainDecoder {
 
     static byte[] joinFragments(List<byte[]> fragments, int messageLen) {
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        fragments.forEach(baos::writeBytes);
+        for(byte[] fragment : fragments) {
+            baos.write(fragment, 0, fragment.length);
+        }
         byte[] message = baos.toByteArray();
 
         byte[] unpaddedMessage = new byte[messageLen];
diff --git a/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainUtils.java b/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainUtils.java
index 47e3acf..3eda209 100644
--- a/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainUtils.java
+++ b/src/main/java/com/sparrowwallet/hummingbird/fountain/FountainUtils.java
@@ -2,6 +2,7 @@ package com.sparrowwallet.hummingbird.fountain;
 
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
@@ -15,7 +16,7 @@ public class FountainUtils {
         // others. This means that if you only generate the first `seqLen` parts,
         // then you have all the parts you need to decode the message.
         if(seqNum <= seqLen) {
-            return List.of((int)seqNum - 1);
+            return Collections.singletonList((int)seqNum - 1);
         } else {
             ByteBuffer buffer = ByteBuffer.allocate(Integer.BYTES * 2);
             buffer.putInt((int)(seqNum));
diff --git a/src/test/java/com/sparrowwallet/hummingbird/fountain/FountainCodesTest.java b/src/test/java/com/sparrowwallet/hummingbird/fountain/FountainCodesTest.java
index be6d98d..85372fe 100644
--- a/src/test/java/com/sparrowwallet/hummingbird/fountain/FountainCodesTest.java
+++ b/src/test/java/com/sparrowwallet/hummingbird/fountain/FountainCodesTest.java
@@ -24,7 +24,7 @@ public class FountainCodesTest {
     @Test
     public void testRandomSampler() {
         RandomXoshiro256StarStar rng = new RandomXoshiro256StarStar("Wolf");
-        RandomSampler randomSampler = new RandomSampler(List.of(1d, 2d, 4d, 8d));
+        RandomSampler randomSampler = new RandomSampler(Arrays.asList(1d, 2d, 4d, 8d));
         int[] numbers = IntStream.range(0, 500).map(i -> randomSampler.next(rng)).toArray();
         int[] expectedNumbers = new int[] {3, 3, 3, 3, 3, 3, 3, 0, 2, 3, 3, 3, 3, 1, 2, 2, 1, 3, 3, 2, 3, 3, 1, 1, 2, 1, 1, 3, 1, 3, 1, 2, 0, 2, 1, 0, 3, 3, 3, 1, 3, 3, 3, 3, 1, 3, 2, 3, 2, 2, 3, 3, 3, 3, 2, 3, 3, 0, 3, 3, 3, 3, 1, 2, 3, 3, 2, 2, 2, 1, 2, 2, 1, 2, 3, 1, 3, 0, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 1, 3, 3, 2, 0, 2, 2, 3, 1, 1, 2, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 2, 3, 1, 2, 1, 1, 3, 1, 3, 2, 2, 3, 3, 3, 1, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 2, 3, 3, 1, 2, 3, 3, 1, 3, 2, 3, 3, 3, 2, 3, 1, 3, 0, 3, 2, 1, 1, 3, 1, 3, 2, 3, 3, 3, 3, 2, 0, 3, 3, 1, 3, 0, 2, 1, 3, 3, 1, 1, 3, 1, 2, 3, 3, 3, 0, 2, 3, 2, 0, 1, 3, 3, 3, 2, 2, 2, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 2, 0, 2, 3, 3, 3, 3, 2, 1, 1, 1, 2, 1, 3, 3, 3, 2, 2, 3, 3, 1, 2, 3, 0, 3, 2, 3, 3, 3, 3, 0, 2, 2, 3, 2, 2, 3, 3, 3, 3, 1, 3, 2, 3, 3, 3, 3, 3, 2, 2, 3, 1, 3, 0, 2, 1, 3, 3, 3, 3, 3, 3, 3, 3, 1, 3, 3, 3, 3, 2, 2, 2, 3, 1, 1, 3, 2, 2, 0, 3, 2, 1, 2, 1, 0, 3, 3, 3, 2, 2, 3, 2, 1, 2, 0, 0, 3, 3, 2, 3, 3, 2, 3, 3, 3, 3, 3, 2, 2, 2, 3, 3, 3, 3, 3, 1, 1, 3, 2, 2, 3, 1, 1, 0, 1, 3, 2, 3, 3, 2, 3, 3, 2, 3, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 1, 2, 3, 3, 2, 2, 2, 2, 3, 3, 2, 0, 2, 1, 3, 3, 3, 3, 0, 3, 3, 3, 3, 2, 2, 3, 1, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 2, 1, 3, 3, 3, 3, 2, 2, 0, 1, 2, 3, 2, 0, 3, 3, 3, 3, 3, 3, 1, 3, 3, 2, 3, 2, 2, 3, 3, 3, 3, 3, 2, 2, 3, 3, 2, 2, 2, 1, 3, 3, 3, 3, 1, 2, 3, 2, 3, 3, 2, 3, 2, 3, 3, 3, 2, 3, 1, 2, 3, 2, 1, 1, 3, 3, 2, 3, 3, 2, 3, 3, 0, 0, 1, 3, 3, 2, 3, 3, 3, 3, 1, 3, 3, 0, 3, 2, 3, 3, 1, 3, 3, 3, 3, 3, 3, 3, 0, 3, 3, 2};
 
@@ -36,7 +36,7 @@ public class FountainCodesTest {
         RandomXoshiro256StarStar rng = new RandomXoshiro256StarStar("Wolf");
         List<Integer> numbers = IntStream.range(1, 11).boxed().collect(Collectors.toList());
         numbers = FountainUtils.shuffled(numbers, rng);
-        List<Integer> expectedNumbers = List.of(6, 4, 9, 3, 10, 5, 7, 8, 1, 2);
+        List<Integer> expectedNumbers = Arrays.asList(6, 4, 9, 3, 10, 5, 7, 8, 1, 2);
 
         Assert.assertEquals(expectedNumbers, numbers);
     }
diff --git a/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoAccountTest.java b/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoAccountTest.java
index 5b40158..4db4606 100644
--- a/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoAccountTest.java
+++ b/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoAccountTest.java
@@ -9,6 +9,8 @@ import com.sparrowwallet.hummingbird.UREncoder;
 import org.junit.Assert;
 import org.junit.Test;
 
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 public class CryptoAccountTest {
@@ -21,7 +23,7 @@ public class CryptoAccountTest {
         Assert.assertEquals("37b5eed4", TestUtils.bytesToHex(cryptoAccount.getMasterFingerprint()));
 
         CryptoOutput cryptoOutput1 = cryptoAccount.getOutputDescriptors().get(0);
-        Assert.assertEquals(List.of(ScriptExpression.PUBLIC_KEY_HASH), cryptoOutput1.getScriptExpressions());
+        Assert.assertEquals(Collections.singletonList(ScriptExpression.PUBLIC_KEY_HASH), cryptoOutput1.getScriptExpressions());
         Assert.assertEquals("03eb3e2863911826374de86c231a4b76f0b89dfa174afb78d7f478199884d9dd32", TestUtils.bytesToHex(cryptoOutput1.getHdKey().getKey()));
         Assert.assertEquals("6456a5df2db0f6d9af72b2a1af4b25f45200ed6fcc29c3440b311d4796b70b5b", TestUtils.bytesToHex(cryptoOutput1.getHdKey().getChainCode()));
         Assert.assertEquals("44'/0'/0'", cryptoOutput1.getHdKey().getOrigin().getPath());
@@ -29,7 +31,7 @@ public class CryptoAccountTest {
         Assert.assertNull(cryptoOutput1.getHdKey().getChildren());
 
         CryptoOutput cryptoOutput2 = cryptoAccount.getOutputDescriptors().get(1);
-        Assert.assertEquals(List.of(ScriptExpression.SCRIPT_HASH, ScriptExpression.WITNESS_PUBLIC_KEY_HASH), cryptoOutput2.getScriptExpressions());
+        Assert.assertEquals(Arrays.asList(ScriptExpression.SCRIPT_HASH, ScriptExpression.WITNESS_PUBLIC_KEY_HASH), cryptoOutput2.getScriptExpressions());
         Assert.assertEquals("02c7e4823730f6ee2cf864e2c352060a88e60b51a84e89e4c8c75ec22590ad6b69", TestUtils.bytesToHex(cryptoOutput2.getHdKey().getKey()));
         Assert.assertEquals("9d2f86043276f9251a4a4f577166a5abeb16b6ec61e226b5b8fa11038bfda42d", TestUtils.bytesToHex(cryptoOutput2.getHdKey().getChainCode()));
         Assert.assertEquals("49'/0'/0'", cryptoOutput2.getHdKey().getOrigin().getPath());
@@ -37,7 +39,7 @@ public class CryptoAccountTest {
         Assert.assertNull(cryptoOutput2.getHdKey().getChildren());
 
         CryptoOutput cryptoOutput3 = cryptoAccount.getOutputDescriptors().get(2);
-        Assert.assertEquals(List.of(ScriptExpression.WITNESS_PUBLIC_KEY_HASH), cryptoOutput3.getScriptExpressions());
+        Assert.assertEquals(Collections.singletonList(ScriptExpression.WITNESS_PUBLIC_KEY_HASH), cryptoOutput3.getScriptExpressions());
         Assert.assertEquals("03fd433450b6924b4f7efdd5d1ed017d364be95ab2b592dc8bddb3b00c1c24f63f", TestUtils.bytesToHex(cryptoOutput3.getHdKey().getKey()));
         Assert.assertEquals("72ede7334d5acf91c6fda622c205199c595a31f9218ed30792d301d5ee9e3a88", TestUtils.bytesToHex(cryptoOutput3.getHdKey().getChainCode()));
         Assert.assertEquals("84'/0'/0'", cryptoOutput3.getHdKey().getOrigin().getPath());
@@ -45,7 +47,7 @@ public class CryptoAccountTest {
         Assert.assertNull(cryptoOutput3.getHdKey().getChildren());
 
         CryptoOutput cryptoOutput4 = cryptoAccount.getOutputDescriptors().get(3);
-        Assert.assertEquals(List.of(ScriptExpression.SCRIPT_HASH), cryptoOutput4.getScriptExpressions());
+        Assert.assertEquals(Collections.singletonList(ScriptExpression.SCRIPT_HASH), cryptoOutput4.getScriptExpressions());
         Assert.assertEquals("035ccd58b63a2cdc23d0812710603592e7457573211880cb59b1ef012e168e059a", TestUtils.bytesToHex(cryptoOutput4.getHdKey().getKey()));
         Assert.assertEquals("88d3299b448f87215d96b0c226235afc027f9e7dc700284f3e912a34daeb1a23", TestUtils.bytesToHex(cryptoOutput4.getHdKey().getChainCode()));
         Assert.assertEquals("45'", cryptoOutput4.getHdKey().getOrigin().getPath());
@@ -53,7 +55,7 @@ public class CryptoAccountTest {
         Assert.assertNull(cryptoOutput4.getHdKey().getChildren());
 
         CryptoOutput cryptoOutput5 = cryptoAccount.getOutputDescriptors().get(4);
-        Assert.assertEquals(List.of(ScriptExpression.SCRIPT_HASH, ScriptExpression.WITNESS_SCRIPT_HASH), cryptoOutput5.getScriptExpressions());
+        Assert.assertEquals(Arrays.asList(ScriptExpression.SCRIPT_HASH, ScriptExpression.WITNESS_SCRIPT_HASH), cryptoOutput5.getScriptExpressions());
         Assert.assertEquals("032c78ebfcabdac6d735a0820ef8732f2821b4fb84cd5d6b26526938f90c050711", TestUtils.bytesToHex(cryptoOutput5.getHdKey().getKey()));
         Assert.assertEquals("7953efe16a73e5d3f9f2d4c6e49bd88e22093bbd85be5a7e862a4b98a16e0ab6", TestUtils.bytesToHex(cryptoOutput5.getHdKey().getChainCode()));
         Assert.assertEquals("48'/0'/0'/1'", cryptoOutput5.getHdKey().getOrigin().getPath());
@@ -61,7 +63,7 @@ public class CryptoAccountTest {
         Assert.assertNull(cryptoOutput5.getHdKey().getChildren());
 
         CryptoOutput cryptoOutput6 = cryptoAccount.getOutputDescriptors().get(5);
-        Assert.assertEquals(List.of(ScriptExpression.WITNESS_SCRIPT_HASH), cryptoOutput6.getScriptExpressions());
+        Assert.assertEquals(Collections.singletonList(ScriptExpression.WITNESS_SCRIPT_HASH), cryptoOutput6.getScriptExpressions());
         Assert.assertEquals("0260563ee80c26844621b06b74070baf0e23fb76ce439d0237e87502ebbd3ca346", TestUtils.bytesToHex(cryptoOutput6.getHdKey().getKey()));
         Assert.assertEquals("2fa0e41c9dc43dc4518659bfcef935ba8101b57dbc0812805dd983bc1d34b813", TestUtils.bytesToHex(cryptoOutput6.getHdKey().getChainCode()));
         Assert.assertEquals("48'/0'/0'/2'", cryptoOutput6.getHdKey().getOrigin().getPath());
diff --git a/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoBip39Test.java b/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoBip39Test.java
index 1c87eb0..871b089 100644
--- a/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoBip39Test.java
+++ b/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoBip39Test.java
@@ -7,6 +7,7 @@ import com.sparrowwallet.hummingbird.TestUtils;
 import org.junit.Assert;
 import org.junit.Test;
 
+import java.util.Arrays;
 import java.util.List;
 
 public class CryptoBip39Test {
@@ -16,7 +17,7 @@ public class CryptoBip39Test {
         byte[] data = TestUtils.hexToBytes(hex);
         List<DataItem> items = CborDecoder.decode(data);
         CryptoBip39 cryptoSeed = CryptoBip39.fromCbor(items.get(0));
-        Assert.assertEquals(List.of("shield", "group", "erode", "awake", "lock", "sausage", "cash", "glare", "wave", "crew", "flame", "glove"), cryptoSeed.getWords());
+        Assert.assertEquals(Arrays.asList("shield", "group", "erode", "awake", "lock", "sausage", "cash", "glare", "wave", "crew", "flame", "glove"), cryptoSeed.getWords());
         Assert.assertEquals("en", cryptoSeed.getLanguage());
     }
 }
diff --git a/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoOutputTest.java b/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoOutputTest.java
index 8936bec..0f047f3 100644
--- a/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoOutputTest.java
+++ b/src/test/java/com/sparrowwallet/hummingbird/registry/CryptoOutputTest.java
@@ -7,6 +7,8 @@ import com.sparrowwallet.hummingbird.TestUtils;
 import org.junit.Assert;
 import org.junit.Test;
 
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 public class CryptoOutputTest {
@@ -16,7 +18,7 @@ public class CryptoOutputTest {
         byte[] data = TestUtils.hexToBytes(hex);
         List<DataItem> items = CborDecoder.decode(data);
         CryptoOutput cryptoOutput = CryptoOutput.fromCbor(items.get(0));
-        Assert.assertEquals(List.of(ScriptExpression.PUBLIC_KEY_HASH), cryptoOutput.getScriptExpressions());
+        Assert.assertEquals(Collections.singletonList(ScriptExpression.PUBLIC_KEY_HASH), cryptoOutput.getScriptExpressions());
         Assert.assertEquals("02c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5", TestUtils.bytesToHex(cryptoOutput.getEcKey().getData()));
     }
 
@@ -26,7 +28,7 @@ public class CryptoOutputTest {
         byte[] data = TestUtils.hexToBytes(hex);
         List<DataItem> items = CborDecoder.decode(data);
         CryptoOutput cryptoOutput = CryptoOutput.fromCbor(items.get(0));
-        Assert.assertEquals(List.of(ScriptExpression.SCRIPT_HASH, ScriptExpression.WITNESS_PUBLIC_KEY_HASH), cryptoOutput.getScriptExpressions());
+        Assert.assertEquals(Arrays.asList(ScriptExpression.SCRIPT_HASH, ScriptExpression.WITNESS_PUBLIC_KEY_HASH), cryptoOutput.getScriptExpressions());
         Assert.assertEquals("03fff97bd5755eeea420453a14355235d382f6472f8568a18b2f057a1460297556", TestUtils.bytesToHex(cryptoOutput.getEcKey().getData()));
     }
 
@@ -36,7 +38,7 @@ public class CryptoOutputTest {
         byte[] data = TestUtils.hexToBytes(hex);
         List<DataItem> items = CborDecoder.decode(data);
         CryptoOutput cryptoOutput = CryptoOutput.fromCbor(items.get(0));
-        Assert.assertEquals(List.of(ScriptExpression.SCRIPT_HASH, ScriptExpression.MULTISIG), cryptoOutput.getScriptExpressions());
+        Assert.assertEquals(Arrays.asList(ScriptExpression.SCRIPT_HASH, ScriptExpression.MULTISIG), cryptoOutput.getScriptExpressions());
         Assert.assertNull(cryptoOutput.getHdKey());
         Assert.assertEquals(2, cryptoOutput.getMultiKey().getThreshold());
 
@@ -53,7 +55,7 @@ public class CryptoOutputTest {
         byte[] data = TestUtils.hexToBytes(hex);
         List<DataItem> items = CborDecoder.decode(data);
         CryptoOutput cryptoOutput = CryptoOutput.fromCbor(items.get(0));
-        Assert.assertEquals(List.of(ScriptExpression.PUBLIC_KEY_HASH), cryptoOutput.getScriptExpressions());
+        Assert.assertEquals(Collections.singletonList(ScriptExpression.PUBLIC_KEY_HASH), cryptoOutput.getScriptExpressions());
         Assert.assertEquals("02d2b36900396c9282fa14628566582f206a5dd0bcc8d5e892611806cafb0301f0", TestUtils.bytesToHex(cryptoOutput.getHdKey().getKey()));
         Assert.assertEquals("637807030d55d01f9a0cb3a7839515d796bd07706386a6eddf06cc29a65a0e29", TestUtils.bytesToHex(cryptoOutput.getHdKey().getChainCode()));
         Assert.assertEquals("44'/0'/0'", cryptoOutput.getHdKey().getOrigin().getPath());
@@ -69,7 +71,7 @@ public class CryptoOutputTest {
         byte[] data = TestUtils.hexToBytes(hex);
         List<DataItem> items = CborDecoder.decode(data);
         CryptoOutput cryptoOutput = CryptoOutput.fromCbor(items.get(0));
-        Assert.assertEquals(List.of(ScriptExpression.WITNESS_SCRIPT_HASH, ScriptExpression.MULTISIG), cryptoOutput.getScriptExpressions());
+        Assert.assertEquals(Arrays.asList(ScriptExpression.WITNESS_SCRIPT_HASH, ScriptExpression.MULTISIG), cryptoOutput.getScriptExpressions());
         Assert.assertNull(cryptoOutput.getHdKey());
         Assert.assertEquals(1, cryptoOutput.getMultiKey().getThreshold());