Fix MultiBuffer decode test

Author: silvanocerza

src/main/java/com/maxmind/db/MultiBuffer.java

@@ -279,10 +279,15 @@ long readFrom(FileChannel channel, int chunkSize) throws IOException {
     @Override
     public String decode(CharsetDecoder decoder)
             throws CharacterCodingException {
+        return this.decode(decoder, Integer.MAX_VALUE);
+    }
+
+    String decode(CharsetDecoder decoder, int maxCharBufferSize)
+            throws CharacterCodingException {
         long remainingBytes = limit - position;
 
-        // Cannot allocate more than Integer.MAX_VALUE for CharBuffer
-        if (remainingBytes > Integer.MAX_VALUE) {
+        // Cannot allocate more than maxCharBufferSize for CharBuffer
+        if (remainingBytes > maxCharBufferSize) {
             throw new IllegalStateException(
                     "Decoding region too large to fit in a CharBuffer: " + remainingBytes
             );

src/test/java/com/maxmind/db/MultiBufferTest.java

@@ -321,9 +321,11 @@ public void testDecodeString() throws CharacterCodingException {
 
     @Test
     public void testDecodeStringTooLarge() {
-        MultiBuffer buffer = new MultiBuffer((long) Integer.MAX_VALUE + 1, 1024);
+        MultiBuffer buffer = createBuffer(65);
+        buffer.position(62);
+        buffer.limit(89);
         assertThrows(IllegalStateException.class, () ->
-                buffer.decode(StandardCharsets.UTF_8.newDecoder()));
+                buffer.decode(StandardCharsets.UTF_8.newDecoder(), 20));
     }
 
     @Test