Receiver respects keepalives.

 + minor enhancements.

src/main/java/net/quedex/api/common/MessageReceiver.java

@@ -15,6 +15,7 @@ public abstract class MessageReceiver {
 
     public static final ObjectMapper OBJECT_MAPPER = new ObjectMapper()
             .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+    private static final String KEEPALIVE_STR = "keepalive";
 
     private final Logger logger;
 
@@ -27,6 +28,12 @@ protected MessageReceiver(Logger logger) {
     protected abstract void processData(String data) throws IOException, PGPExceptionBase;
 
     public final void processMessage(String message) {
+
+        if (KEEPALIVE_STR.equals(message)) {
+            logger.trace(KEEPALIVE_STR);
+            return;
+        }
+
         try {
             JsonNode metaJson = OBJECT_MAPPER.readTree(message);
 

src/main/java/net/quedex/api/market/Quotes.java

@@ -57,8 +57,12 @@ public int getInstrumentId() {
         return instrumentId;
     }
 
-    public PriceQuantity getLast() {
-        return new PriceQuantity(last, lastQuantity);
+    public BigDecimal getLast() {
+        return last;
+    }
+
+    public int getLastQuantity() {
+        return lastQuantity;
     }
 
     public Optional<PriceQuantity> getBid() {