feat: changed method getLockWhitelistEntryByIndex so it returns an optional

Author: julianlen

rskj-core/src/main/java/co/rsk/peg/Bridge.java

@@ -1037,14 +1037,14 @@ public String getLockWhitelistAddress(Object[] args) {
         logger.trace("getLockWhitelistAddress");
 
         int index = ((BigInteger) args[0]).intValue();
-        LockWhitelistEntry entry = bridgeSupport.getLockWhitelistEntryByIndex(index);
+        Optional<LockWhitelistEntry> entry = bridgeSupport.getLockWhitelistEntryByIndex(index);
 
-        if (entry == null) {
+        if (entry.isEmpty()) {
             // Empty string is returned when address is not found
             return "";
         }
 
-        return entry.address().toBase58();
+        return entry.get().address().toBase58();
     }
 
     public long getLockWhitelistEntryByAddress(Object[] args) {

rskj-core/src/main/java/co/rsk/peg/BridgeSupport.java

@@ -2121,7 +2121,7 @@ public Integer getLockWhitelistSize() {
         return whitelistSupport.getLockWhitelistSize();
     }
 
-    public LockWhitelistEntry getLockWhitelistEntryByIndex(int index) {
+    public Optional<LockWhitelistEntry> getLockWhitelistEntryByIndex(int index) {
         return whitelistSupport.getLockWhitelistEntryByIndex(index);
     }
 

rskj-core/src/main/java/co/rsk/peg/whitelist/WhitelistSupport.java

@@ -28,7 +28,7 @@ public interface WhitelistSupport {
      * @return the whitelist entry stored at the given index, or null if index is out of
      * bounds
      */
-    LockWhitelistEntry getLockWhitelistEntryByIndex(int index);
+    Optional<LockWhitelistEntry> getLockWhitelistEntryByIndex(int index);
 
     /**
      * Returns the lock whitelist entry for a given address, or null if the address is not whitelisted

rskj-core/src/main/java/co/rsk/peg/whitelist/WhitelistSupportImpl.java

@@ -45,16 +45,16 @@ public int getLockWhitelistSize() {
     }
 
     @Override
-    public LockWhitelistEntry getLockWhitelistEntryByIndex(int index) {
+    public Optional<LockWhitelistEntry> getLockWhitelistEntryByIndex(int index) {
         List<LockWhitelistEntry> entries = storageProvider.getLockWhitelist(
             activations,
             networkParameters
         ).getAll();
 
         if (index < 0 || index >= entries.size()) {
-            return null;
+            return Optional.empty();
         }
-        return entries.get(index);
+        return Optional.ofNullable(entries.get(index));
     }
 
     @Override

rskj-core/src/test/java/co/rsk/peg/BridgeSupportTest.java

@@ -203,9 +203,11 @@ void getLockWhitelistSize() {
         @Test
         void getLockWhitelistEntryByIndex() {
             LockWhitelistEntry entry = mock(LockWhitelistEntry.class);
-            when(whitelistSupport.getLockWhitelistEntryByIndex(0)).thenReturn(entry);
+            when(whitelistSupport.getLockWhitelistEntryByIndex(0)).thenReturn(Optional.of(entry));
 
-            assertEquals(entry, bridgeSupport.getLockWhitelistEntryByIndex(0));
+            Optional<LockWhitelistEntry> lockWhitelistEntryByIndex = bridgeSupport.getLockWhitelistEntryByIndex(0);
+            assertTrue(lockWhitelistEntryByIndex.isPresent());
+            assertEquals(entry, lockWhitelistEntryByIndex.get());
         }
 
         @Test

rskj-core/src/test/java/co/rsk/peg/whitelist/WhitelistSupportImplTest.java

@@ -68,27 +68,27 @@ void getLockWhitelistSize_whenLockWhitelistHasEntries_shouldReturnOne() {
 
     @Test
     void getLockWhitelistEntryByIndex_whenLockWhitelistIsEmpty_shouldReturnNull() {
-        LockWhitelistEntry actualEntry = whitelistSupport.getLockWhitelistEntryByIndex(0);
+        Optional<LockWhitelistEntry> actualEntry = whitelistSupport.getLockWhitelistEntryByIndex(0);
 
-        assertNull(actualEntry);
+        assertTrue(actualEntry.isEmpty());
     }
 
     @Test
     void getLockWhitelistEntryByIndex_whenLockWhitelistHasEntries_shouldReturnOneOffWhiteListEntry() {
         saveInMemoryStorageOneOffWhiteListEntry();
 
-        LockWhitelistEntry actualLockWhitelistEntry = whitelistSupport.getLockWhitelistEntryByIndex(0);
+        Optional<LockWhitelistEntry> actualLockWhitelistEntry = whitelistSupport.getLockWhitelistEntryByIndex(0);
 
-        assertEquals(btcAddress, actualLockWhitelistEntry.address());
+        assertEquals(btcAddress, actualLockWhitelistEntry.get().address());
     }
 
     @Test
     void getLockWhitelistEntryByIndex_whenIndexIsOutOfBounds_shouldReturnNull() {
         saveInMemoryStorageOneOffWhiteListEntry();
 
-        LockWhitelistEntry actualLockWhitelistEntry = whitelistSupport.getLockWhitelistEntryByIndex(1);
+        Optional<LockWhitelistEntry> actualLockWhitelistEntry = whitelistSupport.getLockWhitelistEntryByIndex(1);
 
-        assertNull(actualLockWhitelistEntry);
+        assertTrue(actualLockWhitelistEntry.isEmpty());
     }
 
     @Test
@@ -318,8 +318,8 @@ void save_whenLockWhitelistIsNull_shouldReturnZeroEntries() {
 
         int actualSize = whitelistSupport.getLockWhitelistSize();
         assertEquals(0, actualSize);
-        assertNull(whitelistSupport.getLockWhitelistEntryByIndex(0));
-        assertNull(whitelistSupport.getLockWhitelistEntryByIndex(1));
+        assertTrue(whitelistSupport.getLockWhitelistEntryByIndex(0).isEmpty());
+        assertTrue(whitelistSupport.getLockWhitelistEntryByIndex(1).isEmpty());
     }
 
     @Test